If you compare the opening of the same page (like Sales Order Card) within the WebClient and the Tablet client, the Tablet Client loads and shows the data 4-times faster usually than the Webclient. Therefore it seems like the Rendering and Scripting Tasks of the WebClient takes way more resources and time.

Could you please improve the performance of the WebClient or introduce an LightWebClient for slower CPUs?

To measure the Time you can use the Chrome DevTools and record the opening command of the Sales Order Page in Cronus.