Can I make the app menu open and respond without animations?

Yes. Set App UI animation speed to 0 under Settings > Application > Advanced Settings & Privacy… to disable transition animations. A smaller nonzero value shortens their duration. Clear the field to restore the displayed default.

This setting applies to app UI transitions, not just the menu. It does not speed up a slow monitor command or resolve every cause of an unresponsive interface. If the menu still stalls with animations disabled, that needs separate investigation rather than another animation adjustment.

You can also change how submenus appear under Settings > Menu > Menu Appearance & Behavior. With Standard presentation, turn off Expanding menu items if you prefer floating submenus instead of sections expanding inside the main menu. Sidebar presentation requires inline expansion, so that option is unavailable there.

If the menu feels crowded, Automatically tidy up app menu keeps only one device's more-options area open at a time. This reduces the amount of expanded content without changing what the display supports.

See timing and animation and menu appearance and behavior for the related preferences.