Summary

Enable front-sync LFB relax and wait stats by default (with env disable), remove unused pending_* counters, add clarifying comments around LFB sync/swap behavior, reduce swap wait stalls on Windows by using a zero‑ms sleep in the swap-complete loop, and avoid redundant fifo_empty_event resets to cut Win32 ResetEvent churn. Improvements target Voodoo 1 and Voodoo 2 behavior, stabilizing menu/gameplay hot spots across multiple titles.

Root Cause

On Voodoo 1/2, LFB reads always forced a full FIFO drain and render-thread idle, even when the CPU was reading from the back buffer. Games like Dungeon Keeper 2 (menu), Descent 2 (Voodoo mode when rockets hit walls), Sub Culture, and Thief issue frequent LFB reads, so the main thread repeatedly stalled the pipeline and speed could drop dramatically (menus down to ~85% or worse, and ~30% in the heaviest cases). The safer relax/frontsync path that avoids unnecessary flushes was only active when the env vars were set manually, so default runs never benefited; enabling it by default (while still forcing sync for front/aux reads) resolves those slowdowns without reintroducing artifacts. On Linux (Wayland), the stalls were far less pronounced and the relax path delivered stable 100% behavior quickly; on Windows, additional latency came from Sleep(1) granularity in the swap‑pending loop and heavy ResetEvent churn on the FIFO empty event. Switching to Sleep(0) and gating fifo_empty_event resets removes those extra Windows‑specific stalls while preserving correctness, bringing Windows behavior in line with the Linux results.

thanks to @unreal9010 for extensive testing across titles.

Checklist

• Closes #xxx
• I have tested my changes locally and validated that the functionality works as intended
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - https://github.com/86Box/roms/pull/changeme/
• This pull request requires changes to the asset set
  • I have opened an assets pull request - https://github.com/86Box/assets/pull/changeme/

References

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