As for lockups, those are not a symptom of Overwatch’s software, so I’d recommend looking at temps and for any third-party apps that are crashing in the background. You can check those with a dxdiag (the error section at the end of the report).
DxDiag instructions (click to expand/collapse)
Reboot your PC, then only open Overwatch and play until you experience the issue. Exit the game, then follow these steps:
Press Windows Key + R, then type DxDiag and press Enter.
In the DxDiag window, click Save All Information.
Name the file “dxdiag” and click Save.
To add it to your reply here:
Open the text file and copy all of the text.
Paste the text in your reply.
Highlight the pasted text and click </> on the post editor.
If your DxDiag does not fit in one message, you can post it on Pastebin.com and provide the hash code (the numbers/letters after the .com) in your reply.