When loading the following paper: https://www.nature.com/articles/s41562-019-0592-8.epdf?author_access_token=P8LH-dm6-WcTUPR6aO7-FtRgN0jAjWel9jnR3ZoTv0PVOC_Ht62aJdy448-TIs1vEHEgxWIZfw6lDOHNp_3r3y8VYCNboUTmS0nPEm2Ws4QGEioiesbzQ34zH5LxsHGwtK5wgRMj2M8LqvCcDgMkMg%3D%3D The performance is atrocious for a while. There's clearly an element of deferred loading impacting the performance, but in chrome the page starts scrolling after quite a delay, and then scrolls smoothly. In Safari, the scrolling remains extremely laggy, and fails to update. Per the inspector we're spending a lot of time in layout and rendering rather than js.
Created attachment 369230 [details] instruments output
Looks to be spending a tonne of time in/under/around CA::CG::draw_glyph_bitmaps(CA::CG::Renderer&, CA::CG::FillGlyphs const&, CA::CG::ShadowStyle const*, bool, bool) Instruments really should develop an understanding of dispatch queues.
<rdar://problem/50529160>
The page seems to be very painting-heavy early on, then at some point get into a good state where it scrolls OK. Maybe rendering the pages lower down is triggering continual full repaints of the pages at the top.
It seems to work fine now in Safari 17.4, is it still reproducible for anyone?
working for me too.