page speed tools – “Avoid landing page redirects”

i know this issue has been discussed before, but i haven’t seen a fix so i thought i’d ask here.

google’s pagespeed tools returns the following error on our site which is using contactform7:

“Avoid landing page redirects for the following chain of redirected URLs.
https://foo.com/?_wpcf7_is_ajax_call=1&_wpcf7=5&_wpcf7_request_ver=1490316905229”

this url redirects to http and then back to https. obviously, i’d like to remove that redirect and improve our score.

any help much appreciated.