the plugin that finally worked is W3 Total Cache. The improvement was very big. But it does not do it automaticaly, well at least in my case it did not.
When you first install it, it gives the options to set all configuration to auto and default. But many times, that doesn’t work, so you have to turn it to manual settings and configure it yourself.
It took me 2-3 days of work, all day long, trying and testing one by one each script. Some times, it gave me a broken website or caused some functionality to be lost, but you can easily remove any script from the configuration or change the sequence, move it up or down, until you make it work. It is a trial end error process.