A drag tick requested the loupe's draft and the frame ended; the draft,
done in 1.5-3 ms on the GPU, was picked up at the start of the next frame,
a frame after the slider moved. Now, in a drag, the loupe waits up to 40 %
of a frame for its draft when the last loupe render took well under that
(not with a render offload, nor zoomed in, where what changes on screen is
the window's draft). A CPU render, which would only make the frame late, is
not waited for.
JobPool::wait waits for the next finished job, which try_recv then hands
out; Renderer::poll's collection of finished jobs is split out so the wait
can turn the draft into the texture.
Co-Authored-By: Claude <noreply@anthropic.com>
