After updating to the latest client and joining some servers running R11 I noticed my "enter battle" was lagging a lot. One of the DICE devs posted a possible fix for this and it worked for me. Below is his quote and the link to that thread in case it does not work for you.
http://forums.steampowered.com/forum....php?t=1234596Example of spawn lag: every time you click on "Enter battle", the game freezes for up to 10 seconds.
Example of game settings problems: the game wants to run at 1024x768 or 800x600 and doesn't remember if you change it to something else.
Which of the two above problems are you experiencing?
Do you have an antivirus product installed? (AVG, NOD32, etc)
If yes, can you instruct the antivirus product not to scan & protect your Documents\BFBC2 directory?
If yes, does that help?