Source's custom OT game engine (TypeScriptFTW)

[Source]

just courious did you performed any load tests against your server? If yes which tools and techniques did You used?

Hey. Nah, not really, except after I made PyOTC I logged into my server with 3000 players. This almost maxed out a single CPU core for the server.
Keep in mind these players don't do anything though, they just turn every 30 seconds to not get disconnected, compared to actually alive players, so my server is probably not more optimized than TFS just because it can handle 3000 players - this is 3000 idle only players.

Some good tools to use is Valgrind + KCachegrind to check server performance + check for memory leaks, causes of segfaults, and probably more.
Beyond that I also check the performance of code inside the server code (internal tests) by using timers that tells me how many µs are used for each function call (removed after it's been checked).
This means I know exactly how much actually or potentially expensive operations cost, and so there's no need for load testing.
Cheers.