Hello sbarkan;
A common cause is that the CPU is unusually busy causing the delay.
You can look at your Task Manager utility program.
Look at the Process list to see what program(s) are using the highest percentage of the CPU time.
You can click on the CPU column (or on any column) to sort the programs/processes running the highest percentage of CPU tasks. Click once, and click again to sort in order.
Task Manager
And look at the Performance tab to get an idea how busy the CPU is at any given moment.