This may be simpler than you think
"unaccounted" ususally means you have Vsync enabled, and that most of the frametime is being spent just waiting for for your monitor to refresh.
Vsync is trash, you should turn it off and never turn it on again, ever, in any situation. since Vsync lets you get up to 120fps it leads me to believe that you have a 120hz monitor, so it might not be as bad for you as it is for people with normal displays, but it can still raise your frametime by as much as 8.3333... milliseconds a frame if you're getting less than 120 fps. And your GTX 460(you do have a GTX460, don't you?) should be able to do better than that on that scene.
if vsync isn't on, then it could be your "fps_max" I think that it's 300 by default, but yours might have gotten lowered by a config or something. set it back up to 300 if it isn't already.
It's easier to talk about performance using "frametime" than it is using "fps". So just keep in mind that frametime is the inverse of fps, the higher your frametime the lower your fps.
also, in this screenshot...
I see that your "dynamic light rendering" floater is wayyyyyyyyyyyyyy far to the right, indicating that in a previous frame you spent 11milliseconds of frametime JUST on switching dynamic lights. That's longer than all other elements in the scene combined... then multipled a few times. In fact, it's almost
taking up as much time as Vsync is, so if you turn off vsync and get rid if your dynamic lights, you'll more than double your framerate in many areas. Pretty good for such little work, eh?
You have to get rid of the flickering lights though, this is not optional. So you need to go through your map, and removed any named light, then remove any kind of flicker than any of them may have. This is good general advice too. Most of the time people overuse dynamic lighting(and any use is really an overuse in source), it's because they're doing something silly or ugly, like putting blinking lights around flames or something. You'll notice that valve maps never have blink lights.
An easy way to do this is to just click the "view entities in map", or whatever button found in one of the dropdown menus in hammer. I can't remember the exact name for it since I haven't mapped in a while, but it's in there. Then scroll down to the "lights" click on the first one, then shift click
on the last one in the list, then hit alt enter, it'll bring up the info for every light, and stick it into one box. change the entity name, and change the flicker dropdown to "none". Then do the same thing for the other light entities you use, like light spot or whatever.
The reason for this is that in older versions of source (before alienswarm) any time you had a "dynamic light" it would stress your CPU and Ram because you'd have to swap out a large chunk of the lightmaps in the scene every time the light changed. This takes a long time and doesn't use the power of your GPU, so you become massively CPU and Ram limited. This also means that the larger your dynamic lights, the longer it takes to swap them because you need to swap more "luxels" which are basically pixels in the lightmap, which are texels in the scene... but the terminology isn't important. This also means that how frequently you change them also affects performance, so if your dynamic lights light up a large area AND they flicker a lot, then you're in for a whole world of hurt.
The plus side to removing those dynamic lights is that your lighting will look a little better, in order to mitigate some of the impact that dynamic lights have on framerate, valve made it so that dynamic lights don't bounce when compiling VRAD. And you want some light bounce, it looks nice.
Your framerate after you make these changes should be pretty good, but if you want to get you compile time down, then you'll need to do me a favor.
Go into hammer, and turn off visibility for everything except for regular old everyday brushes. Then take screenshots of the map from different angles and post them here, I'll help you cut down the number of VISleaves, which will help performance and can cut compile Vis time down to a couple of minutes (or seconds). Also be sure to "load portal file" in one of the dropdown menus, and take a couple more screenshots with the portal file loaded. It should fill your map with a bunch of ugly blue lines.
Since Players in TF2 can jump pretty high, and because TF2 maps are pretty open, there aren't too many optimization techniques that you can use to get a lot of performance back. It mostly comes down to cutting down visleaves and hinting out the right above tall buildings. Which I'll help you do.
Also, the showbudget panel is too small by default (no idea why valve did this) you can use the "budget_panel_height" and "budget_panel_width" command to make it taller and wider. The size is defined in pixels, so it's resolution dependent.
Performance and optimization is kinda my thing. I wish more people would ask why their maps were running poorly and try to fix it, as you are, instead of just releasing ugly maps that run like shit on supercomputers.