Wednesday's Catalyst 10.5 drivers were intended to include the fix for Bad Company 2's long load times, previously available in the 10.4 Preview drivers. ATI are only human, though, and overlooked the fix, excluding it from that release.
Not to worry, though -- quick on the job, just now they've released a hotfix driver set, comprising the 10.5 drivers and the fix. Note this applies to 2xxx, 3xxx and 4xxx series cards running under Windows Vista or 7.
Head to the source to grab it, and remember to uninstall the old set before installing the new.