Method breakpoints will slow down debugger a lot because of the JVM design, they are expensive to evaluate. Remove method breakpoints and consider using the regular line breakpoints. To verity that you don’t have any method breakpoints open .idea/ file in the project root directory (or .iws file if you are using the old project format) and look for any breakpoints inside the method_breakpoints node.
Watch method return values option is enabled in the Debugger Panel. Try disabling this option to improve the performance.
Enable alternative views for Collections classes and Enable toString()’ object view options enabled in Settings | Debugger | Data Views. If toString() methods take a long time to complete, disable this option. Note that custom toString() methods can also change the semantics of the application when running under debugger in case the code inside these methods changes the state of your application.
Memory tab in the debugger toolwindow. It is updated on every debugger stop, try to minimize it to improve stepping performance.
详情可参考：
/hc/en-us/articles/206544799-Java-slow-performance-or-hangups-when-starting-debugger-and-stepping
