I have a few questions that may present a few more ideas

- Are you using the Trackpad? If not, does it behave the same way with the Trackpad?

- If you are using a mouse, which one (are its drivers up to date for El Capitan)? If you have access to a different one, please see if it behaves the same way.

- Do you have a graphics tablet installed and/or plugged in?

- I note you are also a Windows user. Do you have any 3rd party mouse utilities installed to change mouse behaviour?

If you are using anything other than the Trackpad, have a look in the System Preferences for any options that may alter mouse behaviour. While I don't have El Capitan, 3rd party control panels could be along the bottom line. Also, have a look in Trackpad, Mouse and Accessibility (and I think OSX also has a graphics tablet/pen one too) for anything that can be toggled and tested.

AutoCAD also has several settings that may or may not help the matter.

- You can reset AutoCAD for Mac to defaults (scroll down for Mac instructions)

- In AutoCAD Preferences under General, try toggling off OpenGL (in the Graphics section)

- In AutoCAD Preferences under Cursor and Selection, try changing colours, length and sizes of the crosshair

- In AutoCAD Preferences under Units and Guides, try toggling coordinate display, autotrack settings and fields

- In AutoCAD drawing space, try toggling dynaimc input, polar tracking and object snap tracking

Hopefully there is something here that can assist alleviate your problem until a proper solution is found.