Hi Gwen Jamroziak,
I share the same answer of jose,
if you open 7 tabs it's like opening 7 projects consumes too much memory like other programs with C# java among others.
Let's remember that when opening a project in outsystems the component blocks are loaded, action screens themas variable... and everything is loaded by the ram memory and the processor.
If you really need to have more than 7 tabs, you could open another instance of the study service and you would have 7 more tabs.
Greetings.