[meta] Improve initial load time

[sstangl]

OpenWeightlifting currently takes around 4.3 seconds from request initiating to rendering the leaderboard, measured without cache (ctrl-shift-R), with an ad-blocker enabled. OpenPowerlifting takes about 650ms. Faster time to full render makes for a significantly more pleasant user experience.

It looks like the time is currently divided up like this:

• Initial backend render: ~880ms
• Fetch a large number of script assets: ~1500ms
• Script execution: ~1400ms
• Get /leaderboard: ~500ms

This issue is mainly to ask if it would be in-scope to set such a target, and then if so, to work backwards to figure out technical details to meet that target.

[euanwm]

Playing around with Svelte on this as a potential FE replacement as NextJS is the bottleneck.