I am consulting for a site that uses Expression Engine as its content management suite and Apache/LiteSpeed + Varnish with an SQL database.

We are being told that the server is over-capacity (mainly CPU), and that a big part of the problem is that Expression Engine does not play well with Apache.

I am sorry I can't be more specific, but does that sound right? Is that the reputation that Expression Engine has? Compared to WordPress for example, is it really a huge resource hog?

If true, can anything be easily done to improve the situation?

Thanks in advance.