Very high RAM usage

I’m currently using ue4.15 and have an i7k, gtx1080 and 16gb of ram with windows 10, the RAM usage goes upto about 83% and it takes about 40 seconds to add a trigger in a blueprint!

Is this normal, how much more RAM do I need to bring this lag down would 32gb be enough?

My map is pretty straight forward although does have a 2k hdri  and many triggers about 500.

Can someone help?!