USB too slow ???

[nunosantos]

Hello!

Im going directly to the problem.
Im using the ccs code (ex_usb_serial) that examples the use of usb with pic 18f4550. The interface with the user is built in labview.
On the labview side whenever i want to receive data i send a char throw usb to the pic and the pic is waiting for that char in a while loop. When it receives the char it sends again throw usb 5bytes (for example 3f,27 (in hexadecimal)). The problem is that im not getting the sample rate I need to build the wave form. Possible causes anyone?? Ill paste the pic code if necessary.

thanks.