I can confirm this problem, we have experienced it on the Spanish localization for OpenERP 5.0 when undoing the fiscal year closing (the fiscal year closing wizard of the Spanish localization allows to undo the closing operations anytime).
On a normal production database, creating the fiscal year closing move (a big move, as it has a line per non-zeroed account) takes about 2 to 4 seconds, deleting the same move takes 20 to 40 seconds.
I can confirm this problem, we have experienced it on the Spanish localization for OpenERP 5.0 when undoing the fiscal year closing (the fiscal year closing wizard of the Spanish localization allows to undo the closing operations anytime).
On a normal production database, creating the fiscal year closing move (a big move, as it has a line per non-zeroed account) takes about 2 to 4 seconds, deleting the same move takes 20 to 40 seconds.