Investigate slow compilation times

[alexfoxgill]

e28e0070074dc52cfff6ba586c44fa6649885d03

Symbols:     1313985
Types:        788655
Memory used: 911104K
Check time:   78.97s
Total time:   79.67s

6f8e3e75d9de6cde928d877b083559bf8e665448

Symbols:      121139
Types:         67276
Memory used: 131777K
Check time:    2.36s
Total time:    3.19s

without 4-part prop overload:

Symbols:     1085472
Types:        650274
Memory used: 763202K
Check time:   45.22s
Total time:   45.97s

without 3-part:

Symbols:      868055
Types:        522824
Memory used: 619599K
Check time:   27.51s
Total time:   28.21s

without 2-part:

Symbols:      651404
Types:        399632
Memory used: 499634K
Check time:   16.01s
Total time:   16.68s