map size about 20mb when compiled.
fast compile option takes about 15 mins.
full compile ran for about 6hrs and just ended up saying portal flow ...1...2...3

system specs:

3ghz p4
1gb ram
256mb gforce 6800

i closed all open programs, have plenty of hdd space, and set hammer to highest priority yet it slows my pc down to a crawl when doing this full compile and well will likely take several days.
any way to make the thing quicker, and will a full compile actually be worth it?
does it boost fps performance?

Hammer always slows down your computer to incredible cripliness when doing a full compile. This is faaarrr from being any issue. Also, your map may slow down the compiling process if youre using complex brushes (usually because of carving) and bad skyboxes. A bad skybox is basically a huge hollowed-out rectangle around your level, which slows down vis calculations drastically.

Lots of errors can cause the map to cease compiling during the portalflow process. When I was new to mapping I left the first version of claviers going for almost a whole weekend before giving up, and it had reached ...4... or something like that. In the end I totally rebuilt the map from scratch as there were too many brushes to fix.

Likelyhood is you havent turned much if anything to func_detail? The bad brushes that are causing your problem need to be made func_detail or re-made entirely. Maybe if you posted your compile log from the fast compile in here it may tell us more.

Look for errors like WARNING: Cluster portals saw into cluster and FindPortalSide: Couldn't find a good match for which brush to assign to a portal near (x,y,z-coordinates), as I think these are the main offenders.

Ref: http://www.interlopers.net/errors/

i found an item saying

FindPortalSide: Couldn't find a good match for which brush to assign to a portal near (-1122.9, -40.4, 58.0)

how do i find exactly where that is on the map, as i cant see a go to grid option ect there.

and what does the above error mean

Map > goto coordinates.

As Yeti says it's most likely caused by too many world brushes. Use more models and func_detail brushes and less world brushes. If you create any brush with more that 4 sides or/and that does not have 90 degree angles on it you proably have to re-think it.
Check out the Flash_sdk and in the auto-vis groups turn off all tool brushes and func_details and point entities and brush entities and then you can see what the bare world brushes should be like.

Yeah I had the same problem with Battlebridge and was purely down to bad optimisation. Once CoolHand had worked on it a full compile came down from over 5 days, having got stuck on portal flow same as yours, to 3hrs.

Also as Dash mentioned if your skybox is a large rectangular block you need to redo it and bring it down onto rooftops etc and decrease it's size as much as possible. Have a look at how the skybox is done in Donner to get an idea.

Don't give up it can be fixed, just may take some time and alot of patience.

I certainly agree guys,

Func_detail all of your map that doesn't block visibility, eg, your footpaths, fancy detail brushes for building detail, triangular, spherical, and odd shaped brushes (ones that are not square).

It will reduce your V VIS compile time down dramatically and if you optimize using well placed hint brushes your frames per second will get a good kick in the right direction too.

I had tiger up at about 15 hours compile before optimization, after a good few weeks of fixing a lot of brushes and func_detail'ing the odd brush shapes I got it down about 30mins for a FULL compile. (FULL - FINAL compile takes about 6 hours due to VRAD spending more time with the lighting and shadow detail).

TGM

After testing FULL VIS compared to FAST VIS i hav not noticed any difference in performance, occlussion nore lighting detail between the 2

I know that full VIS does more calculation passes than FAST vis but i realy hav not noticed a difference other than compile time . . .