What causes high interrupt to process latency

I could only find the definition of this:

"The interrupt to process latency reflects the measured interval that a usermode process needed to respond to a hardware request from the moment the interrupt service routine started execution. This includes the scheduling and execution of a DPC routine, the signaling of an event and the waking up of a usermode thread from an idle wait state in response to that event."

I couldn't find information as to what would cause problems with it.
I'm using LatencyMon to measure it, and it keeps going up especially during gaming.