Apparently the number of tags alone impacts performance, not just whether the tag is "active". But your mod only adds 6 new tags, there is absolutely no way that could have a noticeable impact on performance. The performance argument, if one is to be made, needs to based on some sort of slippery slope like this:
The argument being that if we add Florence, which would not impact performance significantly enough to be notable, then we would also have to add X number of other tags, which eventually would add up to a performance issue.