Yeah, I did something stupid in my own test. Probably I was thinking about Object.seal(). Nevertheless your own test revision #3 shows that accesses to frozen p

Yeah, I did something stupid in my own test. Probably I was thinking about Object.seal(). Nevertheless your own test revision #3 shows that accesses to frozen properties are roughly 14 times slower. Revisions #5 and #6 do an allocation in the "hot" testcase so the real cost of property lookup just becomes hidden behind cost of memory management.