A lot of game-related media has reported that a lot of games are largely unaffected by Spectre and Meltdown. My impression is that the most common result is "about 3%." (With some notable exceptions, however.)
Does this bode well for Apple code, which seems to tend to pull in innovations from games into the general UI?
The performance issues come from security mitigations when entering/exiting the kernel during syscalls. So I/O heavy workloads such as databases will suffer, whereas heavy compute-oriented tasks such as games should be mostly OK. This is expected. There is nothing any company can do to "take advantage" of the fact that games are cpu/gpu bound in order to mitigate new performance issues in e.g. databases.
Does this bode well for Apple code, which seems to tend to pull in innovations from games into the general UI?