Your AEM instance is running slower and eventually stops with some variation of an out of memory errors or exceptions. You also see errors in the logs similar to the following:
OutOfMemoryError: Java heap spaceorOutOfMemoryError: gc overhead limit exceeded.
Heap memory is the run time data area from which the memory for all java class instances and arrays is allocated. The heap is created when the JVM starts up and may increase or decrease in size while the application runs. The size of the heap can be specified using –Xms VM option.
This blog shows some ways to generate the AEM Heap Dump for analysis as well as possibly sending it as part of your DayCare ticket to Adobe or when trying to collaborate and troubleshoot with other teams.