Too many programmes opening on boot / start up.

By default, all open apps with resume where they were when you restarted. I think there is a checkbox in the Shutdown/Restart dialog to enable/disable that feature.

You can also set which apps open at login with the Login Items in Users & Groups system preferences. Select your user account, then Login Items tab.

Some apps will put themselves into the Login Items. They should have a preference setting to turn that on or off.

Right click on the app icon in the Dock, click Options and uncheck Open at startup.

System Preferences > Users & Groups > Login Items. Remove what you don't want to autostart.