MySQL5 performance

I've just reverted back to php4 & MySQL4 after trying php5 & MySQL5 (all Darwinports).

I found that MySQL5 appeared to be substantially slower than MySQL4. I'm using a php script to trawl through a bunch of text files, and depending on what it finds in each line to ignore it or insert or update a db entry.

MySQL4 achieves a import in about 1 hour 20 mins, MySQL5 takes about 3 hours. The php script is identical, the logfiles are identical, the db structure is identical, the indexes are identical.

I've tried searching for tweaks to my.cnf ... made very little difference ... certainly nothing seems to bring MySQL5 anywhere near MySQL4's time.

There are some forum entries that say about a MacOSX speed bug in the latest MySQL5, but it doesn't say what version(s) are actually affected.

So any ideas?

MacOSX 10.4.7 running on a G4Ti 667 MHz laptop with 1 GB RAM.

Mark