...By lag I mean single player lag...
Playing Singleplayer is a lot harder on your system, particularly the CPU, compared to playing online.
Not only does it have to run the game, but it has to run the server and all the bots as well.
This is your laptop, yeah?:
http://www.dell.com/au/p/alienware-m15x/pdAnd this is the likely problem:
* Intel® CoreTM i7X 940XM Processor (2GHz/8MB cache)
* Intel® CoreTM i7 840QM Processor (1.86GHz/8MB cache)
* Intel® CoreTM i7 740QM Processor (1.73GHz/6MB cache
The BF2 engine was written for single core CPU's, and the fastest CPU listed is only running at 2GHz...so as far as the game's concerned you've effectively only got a 2GHz single core CPU.
At that speed you'll probably find you can only have 25-30 bots (@max difficulty) before it starts to lag.
I can't recall what the stock FH2 number of bots/difficulty level is, but if you go into
'...EA Games\Battlefield 2\mods\fh2\ai' and open
aidefault.ai, you can edit both settings:
echo *****************************************************************************************
echo AIDefault.ai ****************************************************************************
echo *****************************************************************************************
aiSettings.setNSides 2
aiSettings.setAutoSpawnBots 1
aiSettings.setMaxNBots 64
aiSettings.maxBotsIncludeHumans 1
aiSettings.setBotSkill 0.4
rem To spawn more than 15 bots in SP, use the following lines instead of the three lines above.
rem Note that this is totaly unsupported, it will affect your system's performance
rem and may even crash your game. That being said, you will most likely be able to run a lot
rem more bots than 15 on your system.
rem Example for 32 bot game with expert bots
aiSettings.overrideMenuSettings 1
aiSettings.setMaxNBots 63
aiSettings.maxBotsIncludeHumans 0
aiSettings.setBotSkill 1.0
run BotNames.ai
aiSettings.setInformationGridDimension 32
run AIPathFinding.ai
rem aiDebug.draw 1
rem EOF
Edit your file (make a backup first) to match this one and try changing the highlighted values, the difficulty level ranges from 0.1 (easy) to 1.0 (hard).
Keep in mind the more bots you have, and the higher the difficulty, the harder it is on the CPU.
And if you haven't already found them, there's also a few downloads for SP you'll want:
http://fhpubforum.warumdarum.de/index.php?topic=6539.0