Nah. While weapons do take away initial FPS, it's not like that. The initial joining FPS is supposed to be the ballpark for all the time cases around town. The super main problem is the memory leak which we solved before. It was great when you used to join the server with 100 FPS and leave with 100 FPS.
Edit: Just ran a server with all addons except for my "modifiedweps" pack which contains third person, sitting, all tools and some general weapons and it boosted my FPS by 20 - 30
Update: Ran some benchmarks with the modified weapons gone and this is what I got
I will look into the 2 most probable causes for this and I will see what happens.
I see.
It seems that a lot of the addons people sell have seriously terrible methods to accomplish some of their tasks, such as trusting the client (a lot of the ATM scripts, for some stupid reason), and some of them can cause a lot of memory leaks. I wouldn't be surprised if it wasn't even a "heavy" soon causing the problem, but rather a poorly written small script. I've seen quite a few myself.