Venue 8 Pro is very slow when CHARGING, scroll web page not smooth. everything is fine if not charging! somebody know why?
You didn't state if only web browsing is slow, or if other tasks are also affected... However, settings in the "Power Options" "Display" & "Network..." Control Panels will affect the way your tablet behaves while charging and when powered by the battery. Even if nothing looks odd about the settings they can become 'silently' corrupted. You can force a refresh of these settings by deliberately making and applying a change, then immediately restoring and saving the default setting. If none of that helps, a hardware issue may be causing that pokey behavior... Are you using the original charger and cable supplied with your tablet? Is the charger, cable or any parts of the tablet noticably warm while charging?
If none of this helps guide you to a solution, you may also request further assistance from Dell Mobility Support. There's a chat option available for customers contacting them from overseas. If Internet Explorer is extremely slow, you might choose to reach them from a different computer initially, but have your tablet nearby...
Dell Venue Pro Support