Well Microsoft does push out feature add/change/removes, but I doubt that's what's happening as it would likely happen to most or all other people with those updates.
Other things it could be
- Hardware problem (such as a failing disk, or overheating CPU) could degrade your performance
- Malware can cause all sorts of issues
- Corruption in your OS
- A buggy driver update
For the office issue I would start by repairing Office
For the performance issue
Test your hard drive (google will give you a lot of free tools) such as speedfan, spinrite, seagate seatools
Run multiple malware scanners preferably in safe mode such as tssdkiller, spybot and malwarebytes
Run some built in tools to check for file system inconsistencies...