looking for an extensible theme with good performance

[daobab]

I have no prior experience with PS however I would like to build a shop with it.
I was thinking about creating my own theme basing on a defualt theme but I guess it would take too much time due to my inexperience with PS and lack of design skills.

Could you reccomend me a theme? 
- it could be paid one
- preferably it should be fast (I noticed that a lot of  paid themes load a lot of js and css files and some of  them are bigger than 100K)
- if it is not so fast it should be easy to slim it down
- it has a blog

Also: is it the best place to look for paid PS themes: https://addons.prestashop.com/pl/3-szablony-prestashop - or should I look somewhere else?

Thanks!