P3D is a pretty awful performing platform when using complex addons, unfortunately. I remember fighting out of memory errors in P3Dv3 with the Concorde, trying to resize all the 2D panels so that they consumed less RAM and that worked to some extent but still, the 4GB VAS issue was a real PITA. Complex addon airports didn’t help either.
Even now with 64-bit P3D there are still issues it seems. The MSFS version is hopefully going to perform better as it should handle RAM more efficiently.