Can slow mobile page speed affect desktop search results?

[lauraballer]

I heard recently from an SEO friend that with Google's recent update, mobile page speed now affects desktop results.

Our site is relatively slow on mobile, and I wanted to check!

Thank you!

[GastonRiera]

Hi Laura,
Hope everything is fine

TLDR; If your site is already in mobile first index, then a slow speed in mobile will affect your rankings.

What you need to know is whether your site is in the mobile-first index or not. You can check that by selecting several pages of your site in the correspondent search console property, through the coverage report looking into the last crawled URLs and clicking in the inspect URL. What to seek, specifically? What says in "Crawled as." Take a look at the attached image.

There you will find out if you are in the desktop first index (crawled mostly as google desktop) or mobile first index.
What does this mean? That your site will be either judged to rank with the desktop or the mobile version. 
If your site is in the mobile-first index and has a poor speed performance in mobile then won't probably rank high.

Hope it helps.
Best luck
Gaston

8Zf3DOv

[effectdigital]

This is a really good answer. You can also look for messages from Google saying that "mobile first indexing" was enabled for your site / GSC property