Where to start...
- your map is 2.4 megs, but you included 18 megs of textures! Totally unnecessary, especailly since it looks like you only used a dozen textures in the first place. Nothing you have here justifies custom textures. Switch everything to the standard Halflife.wad textures so people will only need to d/l the map.
- I think this map might have been too ambitious for your current skill level. It's good that you got the ladder to work, it's really big (I actually said "whoa" out loud when I peaked over a ledge), and the idea of a couple of shattered towers is kinda cool. However, your lack of details spoils it. Overall it's very bland, you have no sound effects, and the low lighting doesn't add anything. Summary: you shouldn't have released this, it wasn't ready.
- considering how simplistic the scenery is, your wpoly is abysmal. I found an area that was 1800.
- if you use people's work (ex. their textures) you should give them credit.
- here's a link to a really good tutorial site.
Especially study the methods to lower framerate (vis blocking). The fact that you were able to compile your map at all is a huge step. Now work on fine tuning your skills.