MySQL 5.5: much slower than 5.1 on Windows

Usually you expect an update to improve what you already have.
Not always.
Especially when moving from MySQL 5.1 to 5.5

I experimented a lot of slowdown, and eventually by reading these posts
http://bugs.mysql.com/bug.php?id=59133
http://bugs.mysql.com/bug.php?id=56585

I got a fix that makes MySQL cache write properly; the default has changed in 5.5 and it commits EVERY write to disk immediately.

The fix: change this parameters in myini file



innodb_support_xa=0
innodb_flush_log_at_trx_commit = 0
sync_binlog=0