What does 以 mean in 也提供了低层级的控制功能以尽可能提高灵活性和性能?
Literally speaking, you could translate 以 into "so that""in order to" or some other words that introduces the goal or objective of something. 

P.S. It seems that this sentence is obtained from direct translation [i.e. word-by-word] with minor modification according to grammar. Usually the structure of these translated Mandarin sentences is fairly close to the that of the original English, so you could try to check each word one-by-one.