Let me save you some time. Check your CPU and Memory usage tomorrow in the resources monitor . Do a CRtl Alt Del , Task manager , performance. First check to see how much CPU usage and Memory TWS is using when open , then see what happens when you open different charts change stock symbols , etc etc . If you see heavy usage on the CPU and Memory then you have to much open in TWS and your computer is having issues handling this. I assume you have at least 16 Gigs of Ram . Any less than 16 Gigs is going to be an issue . I have no lag when I open charts for the two symbols you listed , however with the market being closed I doubt that it would. Finally do you still have the same issues with lag when the markets are closed ?? If you don't have any issues then its definitely a resource issue with TWS requiring to much from your computer because of the amount of stuff you have open