I am writing this after waiting for so long from EPIC to solve this problem. My question is that why EPIC is not addressing this problem that serious.
For me, it started from version 4.19 and it is still there with 4.22. So after 4 versions, it is still taking hell lot of time for shader compiling.
make sure the Engine and the Project in the same Hard disc Drive and it’s will be much better with an SSD drive.