DBugR does have large issues with the way data’s handled. I only really noticed later that I stored it in a very bad way and it meant data (that is, recorded data from profilers) was a lot larger than it needed to be with a lot of repeated text (dictionary based compression gave me a 97% ratio).
Because data was networked to clients, it had very adverse effects on servers. Over time or during spikes of data it could cause clients (all of them) to disconnect because of buffer overflows.
Up until recently, file logging was on by default as well, which meant it would write up to 1mb of data every 30seconds (size depends on how much is profiled), which had very bad performance effects too.
It was too late to change any of that after I noticed, so it needs to be redone. Anyway; it parses DBugR’s effects out, so you can still tell what’s causing performance issues without DBugR itself saturating the results.
FPP is the cause of ~70% of DarkRP’s lag issues (not sure if it still does, but it used to run traces serverside for every player every x milliseconds on every player to find out what prop they were looking at, it’d then network that prop to them). It’s also important to remember source is single threaded, so high end CPU’s are pretty much required. VPS’s tend to have fairly slow CPU speeds in single cores.