Created attachment 181425 [details] screencast ru_RU SUMMARY K-menu feels laggy because submenu highlight doesn't follow mouse immediately. There's a ~120ms delay. STEPS TO REPRODUCE 1. Click on K-menu button to open menu 2. Jiggle mouse pointer up and down over the top-level menu to hover different items. OBSERVED RESULT Upon hovering another top-level menu item, nothing happens for ~120ms (~7 frames for a 60 Hz display), and then 2 things happen around the same time: 1. the highlight moves to the item that was under mouse cursor ~120ms ago 2. the submenu opens for the highlighted item. All in all, it visually behaves the same as using a remote desktop with a 120ms RTT (e.g. transatlantic). EXPECTED RESULT The delay should be much lower, 16ms max. If loading a submenu takes more time (e.g. due to I/O), at least the top-level menu item highlight should update immediately (within 16ms) to make an impression for the user that the UI is responsive. SOFTWARE/OS VERSIONS Operating System: Fedora Linux 41 KDE Plasma Version: 6.3.4 KDE Frameworks Version: 6.13.0 Qt Version: 6.8.2 Kernel Version: 6.13.11-200.fc41.x86_64 (64-bit) Graphics Platform: X11 Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz Memory: 15.4 ГиБ of RAM Graphics Processor 1: Intel® HD Graphics 530 Graphics Processor 2: NVIDIA GeForce GTX 960M ADDITIONAL INFORMATION
Created attachment 181426 [details] kwrite screencast ru_RU For comparison, the menus in KWrite are much more responsive: the highlight lags by 1 frame only (16 ms). See screencast.
Not a duplicate of https://bugs.kde.org/show_bug.cgi?id=483205 because the symptoms are different.
Thank you for the bug report! This issue is already being tracked in another report, so I'm merging the two. *** This bug has been marked as a duplicate of bug 500696 ***