The SX40, and probably most all EVF cameras, are slow if you are used to shooting with an Optical viewfinder camera like most DSLRs. However, it is just noticeable, not a a big deal once you get used to shooting with the SX40 (or 50).
I assume you are talking about focus lag time in the above paragraph. If you are talking about lag time between pressing the shutter release and when the picture is taken, I don't notice that in my copies.
I use the 7D and 5DIII. I bought my SX50 after I bought them and after owning the SX40 already knowing the limitations and advantages of an EVF camera. The SX40 (50) superzooms are welcome additions for me when I use them in situations suitable to them. BIF for example are pretty much out of the question. But most wildlife still shots are excellent.
Also, I find myself using the Macro mode when I need a quick hand-held shot.
It is a great multipurpose camera and the more you use it the better it gets.