Why not let the official nightly or the trunk version build with -O2?

[Loaden]

Here are the test result, I use batch parsing on the codeblocks.cbp.

Without patch and built with -O0
Parsing stage done (1518 total parsed files, 85259 tokens in 0 minute(s), 15.766 seconds).
Parsing stage done (1518 total parsed files, 85259 tokens in 0 minute(s), 10.172 seconds).
Parsing stage done (1518 total parsed files, 85259 tokens in 0 minute(s), 10.203 seconds).

with hash patch and built with -O2
Parsing stage done (1518 total parsed files, 85223 tokens in 0 minute(s), 15.391 seconds).
Parsing stage done (1518 total parsed files, 85223 tokens in 0 minute(s), 7.875 seconds).
Parsing stage done (1518 total parsed files, 85223 tokens in 0 minute(s), 7.813 seconds).

It seems the first time I opened the codeblocks.cbp, the batch parsing
time were really the same. Besize that, performance increased by using
the -O2 options.

My question is:
Why not let the official nightly or the trunk version build with -O2?
The current setting is using -O0?
Since the -O2 option is enough safe and stable and reliable.