delays in receiving and processing BTS message

I have a strange problem , I receive messages using http receive dll on IIS virtual directory and it does not start processing on orchestration until 2 or more minutes after it is received i'm using custom pipeline and Bi开发者_开发技巧zTalk 2009, so anyone can help me please.

i found out that what happened is that BizTalk host increase memory usage incrementally until it reach something like 1,3 GB then it raise memory over follow exception and i should restart all host instances to get back to work