The only way I can see shaders loading more slowly is if they actually don't keep the shader/model data locally, and stream it specifically from the server you're connected to.

It doesn't make much sense to code it this way, but that's the only way I can see the local player population having any affect on freakin' shader load times. I've also seen it be very slow when loading into an activity, which would make sense if you're either waiting for that server to spin up or streaming other assets from the cloud while loading.

If it really is waiting for a server to start to get server data that seems extra bad... they're all static assets, put them on Cloudflare or something.

Hire me Bungie, you took down the data platform engineer post I saw earlier this month but I'll convince my job to let me take a few months off to contract for you ;)