How optimize GMOD server?

For ping there's a couple things to point out. First of all... are you paying for hosting? Are you hosting the server off of your own computer? Are you hosting the server off of your own server box using your internet?

If you are paying for hosting there's not a whole lot you can do besides moving closer to where ever it's being hosted lol. If you live somewhat close to the host and your ping is still a problem, then I would recommend a different host entirely, assuming your internet isn't the problem.

If your hosting a server off of your own pc this is a problem. If you don't have a $2000 computer it would probably reduce the overall lifespan if your running the server constantly. And, if you don't have a crazy internet package from your ISP, everyone will suffer terrible ping.

If your hosting the server off of a dedicated box, you would simply need to increase your internet package with your ISP.

When it comes down to overall server stability this relies on a couple factors.
A). What are the specs of the machine running the server? Is it powerful enough to handle what your trying to do?
If your trying to run something like Helix, Clockwork, Nutscript or any other custom framework, you will have to have more specs then a darkrp server. Having your servers storage space full reduces overall stability as well causing the server responses to be slow. Most hosts don't tell you the specs of the server unless you ask for them. If your planning on running something darkrp based, most hosts should be fine.

B). Not all mods work well together. Have you made sure all your mods don't interfere with each other?
Most of the time, this is not the case. But sometimes conflicting mods can really cause some problems.

C). How many perma props do you have around the map?
Having 20 million perma props and textscreens everywhere will drop players FPS. Not so much for textscreens but props %100.

D). How many random mods do you have players download when they join?
Make sure you remove any un used addons as players with potato PC's have performance issues when trying to play on a server with 5gigs of mods.

And lastly, Optimization

There's not a whole lot you can do to optimize a server. Some things you can do are.
A). Keep your download size low.
This means, keep the file size of your collection small. Most gmod addons are pretty small and you can find a large amount of playermodels less then 1MB, the reason I say this is playermodels are the prime culprit to huge downloads with some models being 500MB on there own. That can easily add up to 5GB's in playermodels without your servers content even downloaded.

B). Look out for broken and conflicting addons
Some addons are straight up buggy and un-optimized. Don't keep an addon because "It's cool and fun" if it's causing freezes, crashes and random other bugs. Conflicting addons will cause random bugs and overall isn't great.