SUMMARY Hello. I've noted that, using Kwrite, (and same with Kate), in some rare condition: * Using bitmap fonts, * And have long strings (> 2k chars each in my case), * And with turned off dynamic word wrap. (View -> Word wrap), i have strong lags when navigating/scrolling large text file. I've shared it here. But, if i `gunzip` the `.pcf.gz` fonts, to make them `.pcf`, (and `fc-cache -fv`), the lags are disappear. I've tested with `ibm-fonts` like 8x8 BIOS font, and with Terminus. I have Archlinux and XFCE; i also confirm this issue on other (similar) machine. I can live with it, as i found this simple workaround with `gunzip`, so severity is low. STEPS TO REPRODUCE 1. Have fresh Archlinux + XFCE. 2. Install `kwrite` and `kate` using `pacman`. 3. Install fonts: `pacman -S terminus-font`; `yay -S ibm-fonts`. 4. Open attached text file using `kwrite`. 5. Settings - Configure Kwrite - Editor font - `Ibm Bios 8x8 wide`. 6. View - Word wrap - turn off Dynamic word wrap. 7. Scroll document (PgUp/PgDn), see lags. 8. Close Kwrite. 9. `cd /usr/share/fonts/misc/` ; `gunzip i*` (use with care, do not run on production machine). `.pcf.gz` fonts should become `.pcf`. 10. `fc-cache -fv` 11. Repeat steps above and see there is no lags any more. OBSERVED RESULT Huge lags when scrolling on normal system (font in its normal `.pcf.gz` state) EXPECTED RESULT No text navigating lags, like using `gunzip` workaround. SOFTWARE/OS VERSIONS Windows: no macOS: no Linux/KDE Plasma: Archlinux + XFCE, but no KDE Plasma yet. KDE Plasma Version: no KDE Frameworks Version: no Qt Version: `qtdiag6` Qt 6.9.1 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 15.1.1 20250425) on "xcb" OS: Arch Linux [linux version 6.15.7-arch1-1] Architecture: x86_64; features: SSE2 SSE3 SSSE3 SSE4.1 SSE4.2 AVX AVX2 RDRAND RDSEED AES Environment: QT_QPA_PLATFORMTHEME="qt5ct" Features: QT_NO_EXCEPTIONS ADDITIONAL INFORMATION 1. Only .bdf/.pcf(.gz) fonts are tested, `.otb` are not tested. 2. There is no any display issues with all these fonts (wrong letters/size/position...), only lags. Thanks to dev teams for valuable and useful work and support.
Created attachment 183376 [details] Large ascii-only text file with long lines
Hi, if unzipping the fonts helps, I don't think we can do anything there. That is then rather a freetype/fontconfig issue. Perhaps it makes sense to report that to the distribution. e.g. NixOS allows to tell that fonts shall be unpacked on install: # fonts for all users fonts = { # add default fonts enableDefaultPackages = true; # ensure we have an emulated global fontdir fontDir = { enable = true; decompressFonts = true; }; ....
Thanks! Use install script is good idea. I am make it works with Archlinux now: https://bbs.archlinux.org/viewtopic.php?pid=2252760 So this issue can be closed now.