I haven't touched wordpress in 8 years, but with old codebases you always inherit a lot of bad design decisions that always have an impact on general performanc

I haven't touched wordpress in 8 years, but with old codebases you always inherit a lot of bad design decisions that always have an impact on general performance. Maybe the wordpress guys have done a great job in rewriting the internals and cleaning things up in the last years, I wouldn't know, I don't follow their progress.