"all"?! No no - not at all - not completely accurate information there. As an example the last UK order you placed that I know about was collected from here (in the UK) yesterday and is in the USA today. Not remotely slow whatsoever, quite the opposite!
Looking at the orders I have sent over the last week, most have already been delivered. Significantly more than half have been delivered within 2 days, across all countries and all shipping speeds selected.
Royal Mail in the UK suffered a cyber attack on its customs handling computer system about 3 weeks ago which did affect items sent via snail mail outside of the UK obviously only for companies that used that particular service. That is back online now for all classes of mail other than economy and not even one single DeLorean Go order has been sent to the USA using that service this year. Every single inland item I sent on Thursday with Royal Mail was delivered on Friday - so that's not affected either.
There are many ways to send various sizes and shapes of box or envelope without using standard mail, which is always slow anyway, and the heavier the order gets, the easier it is to do that, financially.
Yes, it you order a single bolt, and pay say $3 to ship it, it will have to go by standard economy mail, and that might take a month or so, but it often would do anyway even at the best of times, and certainly I don't see many orders like that, and I would always advise people to avoid selecting the absolute slowest service for very small orders unless you really don't care how slow it is.
So I would say "nearly all" orders are completely unaffected - and for those orders of a single bolt or something equally tiny, don't choose the absolute cheapest option, unless you aren't in a hurry.
For orders from other suppliers in the UK, just make sure it's coming by a tracked service, all of which are unaffected.