Investigate recent 32bit compiler performance regressions

In c5088e29 I tweaked the numbers for the x86/Linux build to get them to pass for the RC, but some of these look pretty bad.

Most of them shot up quite a bit. Some of them I don't think were very recent (modification date unspecified, etc.) A few others had updates as early as November, so something has clearly slipped on 32bit platforms here.

I spent a tiny amount of time investigating, but didn't get very far. I'm not holding the RC for these, but it's worth investigating when we get a chance.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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