First things first.. Go and get these compilers..
https://twhl.info/thread/view/17830Then you can use Jack with said compilers.. A batch. file of course always compiles faster but seeing how you're building a supposedly smaller mp map I doubt that it is anywhere near being complex (didn't check your uploaded file).
If your map lags - it is usually due to micro leaks your current compilers won't even detect. One more reason to use the compilers I recommended they got a very good detection system to find such micro leaks. Another benefit is that you get more texture cache and a higher entity limit not to mention several new useful toys to play with for casting shadows and light effects.
the second reason coming to mind could be an absurd amount of flickering lights. During my mod developments I often noticed that my maps lagged also. It often got fixed when conducing a full compile (not a fast compile).
Another aspect is: To conduct your mapping smart and clean. Example below. chaotic mapping where rooms and such aren't separated properly of one another can result in increased compile times and lesser Frames rates per seconds ingame. That being said avoid hallow cubes outside your actual map. Rather go and search/fix the leaks should you have any. Example below:
Mapping real life
There are not many successful real life places that have been mapped. That is because in reality, where we can see is defined by solid objects. In real life we can't see through doors.... But in Half-Life, the Engine can. Actually the engine can see through any entity and will texture the brushes behind it because it thinks you can too! Engine Visibility throughout your map is defined by solid objects. Once again you have to map as though you can see what the Engine can see. Big outdoor places are ok... as long as you don't put anything in them, which sort of defeats the purpose really.
Let's imagine we are in the yard looking back in the window. We can see some of the room. The Engine can see all of the room and some of the hallway because it is trying to show you what you might see if you move. If you have an outdoor map, them most of the inside of your building will be visible by the engine! The more textured surfaces the engine has to render, the slower your map will play.
Mapping for the Engine
As I mentioned earlier, placing a solid (non-entity) brush will block the engine from "seeing" what is on the other side. Well almost. The brush must touch the roof and floor in most cases. But the thing to keep in mind is that if you can see large distances in your map as the player, then the Engine can see more. Most of the large-scale scenic stuff in Half-Life was done through cut-scenes... and a lot of behind the scenes trickery. Ever wondered why you haven't seen a CS_superbowl map? I am not saying it can not be done, I am saying that the engine isn't up to it.
Never texture walls on sides or faces where you the player can't see instead I recommend to texture any walls and segments outside players range with the null texture. Ever wondered why some placed items cause ugly shadows.. Select these brushes and turn them to func_wall or func_detail. You can even group some brushes together to safe up on entity space. In some cases doing that can fix bugs or actually increase the performance as entities are getting compiled differently than solid world brushes.