As far as I am aware of, there is no hebrew translation and for sure there is no translation for version 3.0
The best and quickest way is start translate it yourself, iit should not take more then one day work.
all yo need to do is duplicate all of the files in you App_GlobalResources that ends with .resx without any othe surfix, then just start translate, and recompile all over again. for the RTL solution, just change the body site.css file and add there RTL statement. just easy as that.
After you finish this, you are welcome share us with translation. you can upload it here: http://www.codeplex.com/dashCommerce
Good luck!
P.S:
About the website speed, do you develop on your localhost? in debug mode it will always be slower then on production site. at any case from my expirience, ASP.NET is slower then other platforms such ASP and PHP, but easier to develop with. for each advage there is disadvantage.