Microsoft has always been careless about performance. Two anecdotes:
A friend of mine used to work for Microsoft (long ago). One day I was complaining to him about some package that Microsoft had put out. "It's so slow!" I said. He replied, nonchalantly: "buy Intel stock. People will have to upgrade their PCs!"
Second one is from about 15 years ago. At one of the local meetups, I was chatting with a long-lost friend who worked for Yahoo. He was describing their recently-concluded Search deal with Microsoft, and how it worked in practice. This was an issue he had raised with Microsoft engineers and gotten no traction on their side. (This is all from memory). Basically, he described how a search request from an European user was handled by Yahoo Search. So, say someone goes to "search.yahoo.de" and enters a search term and it triggers a request at some Yahoo server in an EU datacenter. According to the deal, that would be forwarded to a Microsoft server, based in Virginia. Now, since the request was from EU, the Microsoft server would turn around and make a request to a MS server based in EU. Which would then respond with the search results to the MS server in VA. Which would then send the response back to the Yahoo server in EU. So, basically, 4 cross-Atlantic hops for one search request. He claimed latency figures of around 1500ms, when their internal goal was to keep latency below 300ms (after which it becomes noticeable and hurts metrics?). But when he brought up this massive latency spike to his counterparts in MS, they just shrugged it off.