Ryanair operates at least 6 x weekly from BRS to the Canaries with B 737-800s and have been for a number of years. Do they have problems at times? I haven't heard on the grapevine that it's a major issue for them.
It's not common, but certainly not unheard of to have tech stops in Portugal. Strong head winds en route and a high load, coupled with a low QNH, wet runway and reasonably high temperature (>15 celcius) in Bristol can limit performance. Non-standard take off configurations (bleeds off/flap 25) to reduce runway distance required are certainly not uncommon on the Canaries routes.
But that's what happens when you build a short runway on the top of a hill.