I've been doing these for the best part of a decade and it was only in the last couple of years I realised completing a performance review (for me) has been the

I've been doing these for the best part of a decade and it was only in the last couple of years I realised completing a performance review (for me) has been the same as updating your CV - the same advice applies. Just submit a list of single sentences that say things like "Designed and implemented a doodad that saved n hours per day and enabled $BUZZWORD". List the outcomes of things you did this year, use STAR, whatever you prefer. The best part of doing it this way - if they don't give you a nice bonus/raise, you've just updated your CV ready for your next place of work!