Finally finally I've solved this bug (without remove/disable the webkit2 features), in your interner plugins folder remove (or better move to another folder) the JavaAppletPlugin.plugin 😎 this fix the reload bug!
Maybe could be also the Flip4Mac WMV Plugin.webplugin but I think is not this plugin, I don't rememer well because i've deleted from the folder these two plugins 1 week ago and untill now I haven't got any "unwanted reload" (before do it, safari reloaded the tabs 1-2 times any 2-3 hours)
(when you need java you can put again the plugin in the folder, or wait for an update that fix the bug 🙄 )