In the Properties window, go to “Performance tuning.” You will see the default value for “Max MicroKernel Memory Usage” is set to “60” which means 60% of the server memory. See below:

That 60% is what we call the Level 2 cache, which is subject to compression so the PSQL server can hold more data in memory. The Level 1 cache is the value 3247 in Cache Allocation Size in MB, which is about 3.2GB in this case. Level 1 cache is allocated upon startup by the PSQL engine and it is not compressed, so level 1 cache is faster than level 2. Level 2 cache,  even though it is compressed, is still much faster than accessing data from disk. Therefore, you can adjust the values in “Cache Allocation Size in MB” and “Max MicroKernel Memory Usage” to balance between performance and memory usage. Generally speaking, more memory will help out the performance.

In your case, I see you also share Microsoft’s SQL server with PSQL database engine. There are several instances of your SQL server which also takes a significant amount of memory. I see you have several options here: (1) Do nothing. In your example, the server still has some free memory; (2) If you are running out of memory and you can’t control the memory growth from services like the SQL server, then you may want to consider moving SQL servers to a different server; (3) If moving SQL servers is too much efforts, then adding more memory to this server is a good option; (4) Lastly, you can reduce PSQL memory usage by adjusting its memory usage as explained above. This may be easy to do, but not necessary your best option. Your PSQL performance can be affected. But we won’t know the magnitude until you try.

The bottom line is you need sufficient memory to run your server. The above explanations should give you enough information on what to do next.