It's a shame that the live version on Ummagumma isn't one of their better ones.
They tended to either play a "quick" version, lasting between six and seven minutes, or a "slow" version which would last between nine and twelve minutes. Ummagumma contains a "quick" one, probably for reasons of space on the CD. The version on the Pompeii DVD is a "slow" one, but they still didn't jam as much as they did when they were just doing a normal gig. It feels "rushed".
Throughout 1970 they were playing Green Is The Colour and running into CWTAE at to the end of it. However, by 1971 they'd ditched GITC and played CWTAE on its own, which meant that the pace of it wasn't dictated by the speed of GITC before it. Rick's keyboard introduction from 1971 to 1973 is much better that in 1969 and 1970 too. My personal favourite is the performance of 17th on October 1971 in San Diego.
Floyd stopped playing CWTAE at the end of the 1973 US Dark Side tour, as material from Wish You Were Here and future Animals songs were taking over the set for 1974, and they wanted to continue playing Dark Side in the second half. Set The Controls, Atom Heart Mother, Embryo and Saucerful of Secrets had all bitten the dust by this point too. One Of These Days only lasted three years in the live set before Gilmour revived it in 1987.
CWTAE made one final appearance, as a surprise encore on May the 9th, 1977 at the Oakland gig on the Animals tour. Snowy White hadn't even heard of it before so his input on stage was minimal. Naturally the crowd were way too drunk and stoned to care, shouting loudly throughout. Not a very fitting end to one of Floyd's best songs.