Friend incessantly bringing up exam results

[Wantthisfriend]

I have a friend who is constantly brings up how well her DC are doing at school. Sometimes directly saying "they've achieved XYZ" other times saying things like "what does a 1 mean, DC has just got one and I'm not sure if its good" (1 is the best mark they can get at our school).
Trouble is, my DC are very low achievers academically and it crushes me to have to then discuss how 'badly' they are doing. Friend knows their circumstances and is well aware that mine have educational needs, although she once said my DC need to snap out of it and not wallow.
I began feeling happy for her, but 5 years in and it comes up at every report day, term assessment results and sports days, then yesterday, she makes a beeline for me to discuss how rare it is for all DCs in a family to be such high achievers at their age, (all the kids are between 8 and 11). Once, she announced one of her DCs achieving top of the class marks, and when I asked the teacher what my DCs result was, he said the papers hadn't been marked yet.
I know constant bragging like this is a sign of hidden insecurity about something else, but my tolerance for it is wearing thin. Please can you help me to let her know how it makes me feel without sounding like I'm raining on her parade?

Start yawning very loudly

My son has a learning disability and there were a couple of mothers who had children in his class who would ask me how he had got on in tests. I realised they were benchmarking - they needed to know their children had done better than mine.

One day I said 'Oh, [son] didn't do the test!' - Cue, their crestfallen faces, so I couldn't resist and said, 'So which one of yours is bottom if the class?'

They never asked me again!

Tell her she is putting too much pressure on her DC. Our primary school was very competitive and I nearly blinded myself with all the eyerolling I did.

Two choices really. Either give it to her with both barrels, because she is not your friend, as her nasty remark showed -
she once said my DC need to snap out of it and not wallow.

Or if you prefer not, just Grey Rock the fuck out of her, very obviously. A bored "that's nice dear" to every academic boast, even if it doesn't make sense in context, will shut her up eventually.