When a task takes much longer than planned

I am completing yearly performance reviews for my team at work and I find I spend an inordinate amount of time completing them. I am careful to spend time getting the feedback language just right, ensure I reference goals vs results from prior year exactly and provide appropriate development goals for the next year. I believe this work is so important for the development of my team but I procrastinate and avoid doing this work until the last possible minute and then spend what feels like way too much time writing them out. I even seem to buffer while I am writing the reviews by writing, rewriting, researching info, rewriting until I exhaust myself and time runs out. The time I end up spending seems excessive for the end result I produce.

I want to get this work done faster and more effectively but I am getting tripped up with the part that requires subjective feedback not on the part that provides objective data analysis on their performance last year.

Any ideas on what may be going on here?