RetroArch emulates a swap interval above 1 by presenting each frame
that many times, so each frame takes that many of the queue's images.
At 119.88 Hz with the automatic interval of 2, the default three images
held one frame instead of two; the second present of every frame
waited for a vblank on the thread that runs the core, and Dolphin's
frame-stepped emulation ran Wind Waker under ubershaders at 80-99%.
Patch 0091 asks for (video_max_swapchain_images - 1) * interval + 1
images, five by default at 120 Hz: two frames and 33 ms of lookahead,
as three images give at 60 Hz. ../PS5_Vulkan R74 provides them.
Patch count 199 -> 200 (0091's one block).
Evidence: evidence/dolphin-p2-swapchain-before and -after (python3
tools/evidence.py compare). Title 5beca7cc: Profiles 1 and 2 (1x, 6x)
on RE4, Melee and Wind Waker at 100% in every steady window.
verify.sh: all gates pass.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
