Description: Perf: scrolling a large arabic RTL document in multipage view is slower compared to Latin LTR Steps to Reproduce: 1. Open attachment 181658 [details] 2. Go to multipage view, zoom out so at minimum 6 pages fit on screen (sidebar can be closed) 3. Scroll the document with scroll-wheel (laggy) 4. Open some big file for comparison. Like Writer Manual: https://nextcloud.documentfoundation.org/s/G3DqCoDE9bxQ2m2/download?path=%2F&files=WG73-WriterGuide.odt&downloadStartSecret=20ftbxb5z6z 5. Set it again to multi-page view; 6 pages and scroll Actual Results: Performance is slowish Expected Results: Current is not bad, but there is room for improvement Reproducible: Always User Profile Reset: No Additional Info: Version: 7.5.0.0.alpha0+ (x64) / LibreOffice Community Build ID: 86b2bfd34a4f07c54f03c8c8dfe48e0810834628 CPU threads: 4; OS: Windows 6.3 Build 9600; UI render: Skia/Raster; VCL: win Locale: nl-NL (nl_NL); UI: en-US Calc: CL
The attachment document is in Hebrew not Arabic.
So, is this an Arabic issue or an RTL issue?
I don’t know, I couldn’t see a difference in scrolling the two documents. I was looking because Kashida justification in Arabic does not seem to use the glyph cache and I was wondering if it affects performance. Since this is Hebrew, Kashida would be irrelevant.
Created attachment 181760 [details] VerySleepy Screenshot Some very basic perf trace without symbols. Appears to be in TextLayout/ GlyphCache
(In reply to Khaled Hosny from comment #1) > The attachment document is in Hebrew not Arabic. Sorry, me and non-Latin languages.. Next time I put some text snipped into a translator..
Damn it, that's the attachment I posted! It's the guide to the Israeli military prison system. I'm the editor :-P Let me ask you, though - in your LO installation, do you have a font substitution for David? And can you provide a screenshot of the second page (the first one with lots of text)? > zoom out so at minimum 6 pages fit on screen (sidebar can be closed) 6 pages _fully_ fit the view, or 6 pages intersect it? Is it important that 2 full "rows" of pages fit completely?
Created attachment 184958 [details] Perf flamegraph Took a perf trace of showing 6 pages in a row and scrolling by dragging the scrollbar. I see lots of time is spent in SwSubFont::DrawText_ Version: 7.6.0.0.alpha0+ (X86_64) / LibreOffice Community Build ID: 668f55b65849012b359d7d6b9386113facbadc57 CPU threads: 8; OS: Linux 6.1; UI render: default; VCL: kf5 (cairo+xcb) Locale: fi-FI (fi_FI.UTF-8); UI: en-US Calc: threaded
Let's set to new as we have a trace.
I doubt this issue is Hebrew-specific, so hanging on the more general meta-bug