Kanye West -- FourFive Seconds to Bail on Amber Rose

Kanye West was like a human Bugatti -- going zero to 100 in a matter of seconds to get the hell out of Drake's epic party ... when he found out his ex Amber Rose was there too.

We’re told Yeezy was chilling for about 40 minutes, having a good time with folks when the DJ got on the mic and sounded the alarm -- announcing Amber had entered the building.

Sources close to the rapper tell us he wisely didn’t want to chance bumping into her, or worse -- getting photographed near her. We're told Kanye waited for his boys to pinpoint Amber's location ... and then made a quick, quiet exit in the other direction.

The exes beefed earlier this year -- when Amber called Kim Kardashian a whore, and Kayne hit back with his infamous jab about Amber's, umm ... hygiene.

Good thing he didn't have to rinse off this time.