Assuming you're correct, I wonder what caused A to slowly change and become slow like that?
From previously having been a bit innovative?
E.g. the many seconds long load times sounds very unexpected ... How did A change so it now accepts things like that? (Or was it always so -- but we were using Jira 5-6 years ago, don't remember having thought of it as slow)
Everything they have is ready to be overtaken by a disruptive product.