Does the website software effect rankings??

Hi.

I'm currently working on a fairly big project in the mortgage niche in the uk. We have a web guy working for us, he's a good guy but very slow to get things done. This is getting frustrating for us as a lot of changes are going to be needed to be made in the long term.

We want to do the work ourselves however the only software I feel somfortable using to a decent level in serif webplus. It's quite an obscure peice of software but very good for beginners. It's almost like doing desktop publishing but for website. Lots of stuff you can just drag and drop.

I've heard elsewhere though that this makes the code a lot more convoluted than it needs to be and that this can have a negative effects on a sites loading speed. Also I've heard that this can negative effect a sites rankings in google.

Anybody have any thoughts or experiences with this that they can share with me?? It's would take a lot of time to take the site as it is (currently using cms software called umbraco) and convert it into serif.

In my experience I've heard a lot of people say certain thing negatively influence a sites ranking and it ends up being completely untrue when I've tested it myself.

What is every bodies opinions on this?

Thanks a lot.

Dave