OK -
Here's the deal - personally, I have rarely had the issue you describe.
I have listened carefully and thought about this. I also did my own (albeit limited) testing. It looks like the average load time for a Staff user (lots to build for YaBB) runs around 3-5 seconds (acceptable) and the Guest load runs 2-4 seconds (very acceptable). The fact it loads OK for me almost always says - not a bug. Everyone gets the same code, so it has to be one of a limited number of things.
A. General Traffic load related - those in the UK may be on primarily when the server farm is most loaded.
B. Specific node related - even though we have a VPS, it is sitting in a containerized physical server co-residing with other VPS's - we might be sitting on the same node as a UK based e-commerce site for instance.
C. Traffic shaping/routing related. If all our problem loads are geographically close - could be a routing/BGP/Circuit issue. Unless you do a circuit/peering analysis, there no way to understand likely causes in this area.
D. Server Backup related. According to our host, the whole server is being 'tarred' up daily. IF its a 'plain tar' (uncompressed) that's a four hour job, if that was poorly timed - it could be the cause.
Speaking as a systems engineer, I'm betting on 'its time related' in some fashion.
If you have a 'slooooow load', please go to this Topic and note 'roughly how long' to load and the both UTC time it happened & what your local time was. I think we will find a pattern
If you have a good load, also please note the UTC time.
SOOOOOOO - as we know there is nothing wrong with the code, and this is mostly a 'lets see' issue I am going to move it to ServerSide. (where the truly geeky go)
Thanks to everyone -