What the developer wrote
Authored by f321x
qml: skip per-tx balance updates during sync
During synchronization, new_transaction fires for every incoming tx and
each balanceChanged emit makes QML recompute the balance on the GUI
thread. The balance isn't shown anyway during sync.
What changed, and why it matters
This commit is a performance optimization for Electrum's mobile/QML user interface. It prevents the wallet balance from being recalculated and redrawn on every incoming transaction during synchronization, because the balance isn't shown during sync anyway. It is not a security fix and does not change how transactions are validated or stored.
No security action required. Treat as a routine UI performance improvement.
Security signals we found
No strong security signals were identified.
Evidence from the diff
In electrum/gui/qml/qewallet.py, the on_event_wallet_new_transaction handler now only emits balanceChanged when self.wallet.is_up_to_date() is true. During initial sync, new_transaction fires for each historical transaction; previously each emit caused QML to recompute the balance on the GUI thread, producing UI jank. The final balance update is still emitted via on_event_wallet_updated once synchronization completes. No cryptographic, networking, or wallet-state logic is modified.
Changed components
electrum/gui/qml/qewallet.pyQML GUI balance update pathInspect captured patch +4 / −1
diff --git a/electrum/gui/qml/qewallet.py b/electrum/gui/qml/qewallet.py
index eeabf52..35aec4b 100644
--- a/electrum/gui/qml/qewallet.py
+++ b/electrum/gui/qml/qewallet.py
@@ -204,7 +204,10 @@ class QEWallet(AuthMixin, QObject, QtEventListener):
self.add_tx_notification(tx)
self.addressCoinModel.setDirty()
self.historyModel.setDirty() # assuming wallet.is_up_to_date triggers after
- self.balanceChanged.emit()
+ if self.wallet.is_up_to_date():
+ # don't update during sync as this recomputes the balance on each new tx, blocking the UI thread.
+ # on_event_wallet_updated emits balanceChanged once we are up-to-date.
+ self.balanceChanged.emit()
@qt_event_listener
def on_event_adb_tx_height_changed(self, adb, txid, old_height, new_height):
Why this scored 18/100
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