Tabs are ordered alphabetically so you can rename them to make the ones you use the most more accessible.
If you do File > Preferences > Use external editor (check) > OK then you can open the files you need to work with in a text editor and just use the Arduino IDE for compile and upload.
If there are tabs you don't need available for editing in the Arduino IDE you can move them under the src subfolder and update any #include directives accordingly, but be aware you can't do so with .ino files.