test: doc: remove `--perf` profiling from functional test framework

diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index e44a4b91..af242291 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -562,9 +562,8 @@ For IWYU pragmas, prefer adding a nearby source comment that explains why the an
 
 Profiling is a good way to get a precise idea of where time is being spent in
 code. One tool for doing profiling on Linux platforms is called
-[`perf`](https://www.brendangregg.com/perf.html), and has been integrated into
-the functional test framework. Perf can observe a running process and sample
-(at some frequency) where its execution is.
+[`perf`](https://www.brendangregg.com/perf.html). It can observe a running
+process and sample (at some frequency) where its execution is.
 
 Perf installation is contingent on which kernel version you're running; see
 [this thread](https://askubuntu.com/questions/50145/how-to-install-perf-monitoring-tool)
@@ -599,8 +598,6 @@ perf report --stdio | c++filt | less
 
 or using a graphical tool like [Hotspot](https://github.com/KDAB/hotspot).
 
-See the functional test documentation for how to invoke perf within tests.
-
 ### Valgrind
 
 Valgrind is a programming tool for memory debugging, memory leak detection, and
diff --git a/test/README.md b/test/README.md
index 162815d6..0b34f52c 100644
--- a/test/README.md
+++ b/test/README.md
@@ -318,26 +318,6 @@ Often while debugging RPC calls in functional tests, the test might time out bef
 process can return a response. Use `--timeout-factor 0` to disable all RPC timeouts for that particular
 functional test. Ex: `build/test/functional/wallet_hd.py --timeout-factor 0`.
 
-##### Profiling
-
-An easy way to profile node performance during functional tests is provided
-for Linux platforms using `perf`.
-
-Perf will sample the running node and will generate profile data in the node's
-datadir. The profile data can then be presented using `perf report` or a graphical
-tool like [hotspot](https://github.com/KDAB/hotspot).
-
-To generate a profile during test suite runs, use the `--perf` flag.
-
-To see render the output to text, run
-
-```sh
-perf report -i /path/to/datadir/send-big-msgs.perf.data.xxxx --stdio | c++filt | less
-```
-
-For ways to generate more granular profiles, see the README in
-[test/functional](/test/functional).
-
 ### Lint tests
 
 See the README in [test/lint](/test/lint).
diff --git a/test/functional/README.md b/test/functional/README.md
index cf0f2fd0..2de03450 100644
--- a/test/functional/README.md
+++ b/test/functional/README.md
@@ -164,36 +164,3 @@ Test-only secp256k1 elliptic curve implementation
 
 #### [blocktools.py](test_framework/blocktools.py)
 Helper functions for creating blocks and transactions.
-
-### Benchmarking with perf
-
-An easy way to profile node performance during functional tests is provided
-for Linux platforms using `perf`.
-
-Perf will sample the running node and will generate profile data in the node's
-datadir. The profile data can then be presented using `perf report` or a graphical
-tool like [hotspot](https://github.com/KDAB/hotspot).
-
-There are two ways of invoking perf: one is to use the `--perf` flag when
-running tests, which will profile each node during the entire test run: perf
-begins to profile when the node starts and ends when it shuts down. The other
-way is the use the `profile_with_perf` context manager, e.g.
-
-```python
-with node.profile_with_perf("send-big-msgs"):
-    # Perform activity on the node you're interested in profiling, e.g.:
-    for _ in range(10000):
-        node.p2ps[0].send_without_ping(some_large_message)
-```
-
-To see useful textual output, run
-
-```sh
-perf report -i /path/to/datadir/send-big-msgs.perf.data.xxxx --stdio | c++filt | less
-```
-
-#### See also:
-
-- [Installing perf](https://askubuntu.com/q/50145)
-- [Perf examples](https://www.brendangregg.com/perf.html)
-- [Hotspot](https://github.com/KDAB/hotspot): a GUI for perf output analysis
diff --git a/test/functional/test-shell.md b/test/functional/test-shell.md
index 526c67f6..0c2b7d3d 100644
--- a/test/functional/test-shell.md
+++ b/test/functional/test-shell.md
@@ -180,7 +180,6 @@ can be called after the TestShell is shut down.
 | `loglevel` | `INFO` | Logs events at this level and higher. Can be set to `DEBUG`, `INFO`, `WARNING`, `ERROR` or `CRITICAL`. |
 | `nocleanup` | `False` | Cleans up temporary test directory if set to `True` during `shutdown`. |
 | `num_nodes` | `1` | Sets the number of initialized bitcoind processes. |
-| `perf` | False | Profiles running nodes with `perf` for the duration of the test if set to `True`. |
 | `rpc_timeout` | `60` | Sets the RPC server timeout for the underlying bitcoind processes. |
 | `setup_clean_chain` | `False` | A 200-block-long chain is initialized from cache by default. Instead, `setup_clean_chain` initializes an empty blockchain if set to `True`. |
 | `randomseed` | Random Integer | `TestShell().options.randomseed` is a member of `TestShell` which can be accessed during a test to seed a random generator. User can override default with a constant value for reproducible test runs. |
diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
index 1e2ac633..8f5fb239 100755
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -191,8 +191,6 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                             help="Attach a python debugger if test fails")
         parser.add_argument("--usecli", dest="usecli", default=False, action="store_true",
                             help="use bitcoin-cli instead of RPC for all commands")
-        parser.add_argument("--perf", dest="perf", default=False, action="store_true",
-                            help="profile running nodes with perf for the duration of the test")
         parser.add_argument("--valgrind", dest="valgrind", default=False, action="store_true",
                             help="Run binaries under the valgrind memory error detector: Expect at least a ~10x slowdown. Does not apply to previous release binaries.")
         parser.add_argument("--randomseed", type=int,
@@ -292,15 +290,11 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
         should_clean_up = (
             not self.options.nocleanup and
-            self.success != TestStatus.FAILED and
-            not self.options.perf
+            self.success != TestStatus.FAILED
         )
         if should_clean_up:
             self.log.info("Cleaning up {} on exit".format(self.options.tmpdir))
             cleanup_tree_on_exit = True
-        elif self.options.perf:
-            self.log.warning("Not cleaning up dir {} due to perf data".format(self.options.tmpdir))
-            cleanup_tree_on_exit = False
         else:
             self.log.warning("Not cleaning up dir {}".format(self.options.tmpdir))
             cleanup_tree_on_exit = False
@@ -482,7 +476,6 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                 extra_conf=extra_confs[i],
                 extra_args=args,
                 use_cli=self.options.usecli,
-                start_perf=self.options.perf,
                 v2transport=self.options.v2transport,
                 uses_wallet=self.uses_wallet,
             )
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 22d76cac..77a7fcb4 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -18,7 +18,6 @@ import tempfile
 import time
 import urllib.parse
 import collections
-import shlex
 import sys
 from collections.abc import Iterable
 from pathlib import Path
@@ -109,18 +108,11 @@ class TestNode():
         extra_conf=None,
         extra_args=None,
         use_cli=False,
-        start_perf=False,
         version=None,
         v2transport=False,
         uses_wallet=False,
         ipcbind=False,
     ):
-        """
-        Kwargs:
-            start_perf (bool): If True, begin profiling the node with `perf` as soon as
-                the node starts.
-        """
-
         self.index = i
         self.datadir_path = datadir_path
         self.bitcoinconf = self.datadir_path / "bitcoin.conf"
@@ -191,7 +183,6 @@ class TestNode():
 
         self.cli = None
         self.use_cli = use_cli
-        self.start_perf = start_perf
 
         self.running = False
         self.process = None
@@ -200,8 +191,6 @@ class TestNode():
         self.reuse_http_connections = True # Must be set before create_new_rpc_connection(), i.e. before restarting node
         self.url = None
         self.log = logging.getLogger('TestFramework.node%d' % i)
-        # Cache perf subprocesses here by their data output filename.
-        self.perf_subprocesses = {}
 
         self.p2ps = []
 
@@ -298,9 +287,6 @@ class TestNode():
         self.running = True
         self.log.debug("bitcoind started, waiting for RPC to come up")
 
-        if self.start_perf:
-            self._start_perf()
-
     def create_new_rpc_connection(self, *, mode="AUTO", client_timeout=None):
         """Create an additional RPC connection, likely to be used in a new thread."""
         mode = RPCConnectionType[mode]
@@ -490,10 +476,6 @@ class TestNode():
         else:
             self.stop()
 
-        # If there are any running perf processes, stop them.
-        for profile_name in tuple(self.perf_subprocesses.keys()):
-            self._stop_perf(profile_name)
-
         del self.p2ps[:]
 
         assert (not expected_stderr) or wait_until_stopped  # Must wait to check stderr
@@ -679,84 +661,6 @@ class TestNode():
         yield
         self.wait_until(lambda: get_highest_peer_id() > initial_peer_id, timeout=timeout)
 
-    @contextlib.contextmanager
-    def profile_with_perf(self, profile_name: str):
-        """
-        Context manager that allows easy profiling of node activity using `perf`.
-
-        See `test/functional/README.md` for details on perf usage.
-
-        Args:
-            profile_name: This string will be appended to the
-                profile data filename generated by perf.
-        """
-        subp = self._start_perf(profile_name)
-
-        yield
-
-        if subp:
-            self._stop_perf(profile_name)
-
-    def _start_perf(self, profile_name=None):
-        """Start a perf process to profile this node.
-
-        Returns the subprocess running perf."""
-        subp = None
-
-        def test_success(cmd):
-            return subprocess.call(
-                # shell=True required for pipe use below
-                cmd, shell=True,
-                stderr=subprocess.DEVNULL, stdout=subprocess.DEVNULL) == 0
-
-        if platform.system() != 'Linux':
-            self.log.warning("Can't profile with perf; only available on Linux platforms")
-            return None
-
-        if not test_success('which perf'):
-            self.log.warning("Can't profile with perf; must install perf-tools")
-            return None
-
-        if not test_success('readelf -S {} | grep .debug_str'.format(shlex.quote(self.binary))):
-            self.log.warning(
-                "perf output won't be very useful without debug symbols compiled into bitcoind")
-
-        output_path = tempfile.NamedTemporaryFile(
-            dir=self.datadir_path,
-            prefix="{}.perf.data.".format(profile_name or 'test'),
-            delete=False,
-        ).name
-
-        cmd = [
-            'perf', 'record',
-            '-g',                     # Record the callgraph.
-            '--call-graph', 'dwarf',  # Compatibility for gcc's --fomit-frame-pointer.
-            '-F', '101',              # Sampling frequency in Hz.
-            '-p', str(self.process.pid),
-            '-o', output_path,
-        ]
-        subp = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-        self.perf_subprocesses[profile_name] = subp
-
-        return subp
-
-    def _stop_perf(self, profile_name):
-        """Stop (and pop) a perf subprocess."""
-        subp = self.perf_subprocesses.pop(profile_name)
-        output_path = subp.args[subp.args.index('-o') + 1]
-
-        subp.terminate()
-        subp.wait(timeout=10)
-
-        stderr = subp.stderr.read().decode()
-        if 'Consider tweaking /proc/sys/kernel/perf_event_paranoid' in stderr:
-            self.log.warning(
-                "perf couldn't collect data! Try "
-                "'sudo sysctl -w kernel.perf_event_paranoid=-1'")
-        else:
-            report_cmd = "perf report -i {}".format(output_path)
-            self.log.info("See perf output by running '{}'".format(report_cmd))
-
     def assert_start_raises_init_error(self, extra_args=None, expected_msg=None, match=ErrorMatch.FULL_TEXT, *args, **kwargs):
         """Attempt to start the node and expect it to raise an error.