If you login to your Google Search Console account, click on the "Crawl Stats" section under the "Crawl" drop down, you will see the last report that shows time spent downloading a page (in milliseconds) shows a huge drop in the metric.
In the chart below, you can see the average is around 200 milliseconds but then it dropped down to about 75 milliseconds. Here is a screenshot:
Numerous people are reporting this and John Mueller from Google responded on Twitter that he will look into it. Here are some of those complaints:
🤔 Did Google significantly got faster with crawling sites or is the "Time spent downloading a page" data in Search Console broken? /cc @JohnMu @methode @enzenhofer ( big drop for all of my sites. ) pic.twitter.com/giJvm2M2cp
— moreyh 🍁 (@moreyh) February 23, 2018
Don't need to be sorry, same here 🧐 pic.twitter.com/Jadtl3PmyF
— Wojciech Krepa (@wkrepa) February 23, 2018
¿Alguien más ve estas bajadas en los tiempos de carga el 20 de febrero indicados en Search Console? pic.twitter.com/QjouuAte5C
— Sergio Redondo (@sergio_redondo) February 23, 2018
The good news is that you are not alone, it seems to be impacting everyone. Here is how John has responded thus far:
Thanks for the screenshots! I found some other similar examples (and a lot that look normal), I'll check with the team to try to find out more.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) February 23, 2018
I assume it is just one of those many reporting glitches in the Google Search Console.
Forum discussion at Twitter.