It’s not like the pace of technological progress was particularly fast in the Roman Empire and the decline had already started ~200 years before its western hal

It’s not like the pace of technological progress was particularly fast in the Roman Empire and the decline had already started ~200 years before its western half was dissolved. Its collapse wasn’t exactly some straightforward event, it had more or less recovered in many ways by the time of the wars with Persia and the subsequent Muslim invasion (which w arguably the cause of the actual “collapse”). Plague and climate change were seemingly one of the primary causes and Medieval Europeans proved to be much more resilient to both compared to the Romans. There was a gap of a couple of hundred years but Medieval Europeans had surpassed the Romans by 1000 AD both technologically (inarguably) and economically (varied by geographic area).