What would cause a site to be slow to load but only for the first try?

Recently moved my webhosting VMs to a different server in order to be able to update to a newer Proxmox version. It's the same VMs in the same data centre as last one. But now when I try to access my sites it takes a good couple seconds, sometimes like almost a minute for the site to load initially, but after that it's faster to browse. I'm leaning towards DNS but not sure if it really is that as if I do an nslookup it's usually quick. Is there any tools I can use to try to diagnose this further? You can try for yourself to see what I mean: Anything Forums - Anything Forums https://uogateway.com The first try always takes a long time for it to load but once you're on the sites then browsing is fast.