Not necessarily, on modern CPUs memory access is often the bottleneck. If you have many bits storing these in a bitarray can be quite beneficial for performance.
Regardless, due to the way most CPUs work, you almost certainly aren't saving anything by using a bit instead of a byte. When a CPU goes to load a memory address it'll not just get that address, but also the addresses around that address and shove them into cache. With the thought that "If you are loading 1 byte, you are likely loading 128 bytes". The cost savings really only comes into effect when you have more boolean values than bytes that fit in a cache line.