I have single-thread windows form application written with VB.NET and targeting Framework 1.1. The software communicates with external boards through a serial interface, and it mainly consist of a state machine that run some tests, driven in a loop done with a Timer and an Interval of 50ms.

The feedback on the user interface is done through some custom events raised during the tests.

The problem that is driving me crazy is that the performance slightly decrease over time, and in particular after 1200/1300 test operations. The memory occupied does not increase over time, it is only the CPU that seems interested by this problem.

The strange thing is that, targeting framework 2.0 and using the same identical code, I do not have this problem.

I know that is difficult without looking at the code, but do you have suggestions how can I approach the problem?