Hi @radmitry
Thanks so much for posting. This issue is called FOUT (Flash of Unstyled Text) and you can read more on this here: Quick Tip: Avoid FOUT by Adding a Web Font Preloader
You can fix this by adding a bit of custom code to your site — Dave explains this more here: Flash of unstyled text - fallback fonts loads initially then switches to google font - #7 by cyberdave.
Alternatively, you can try downloading the Google font, then uploading it to your site as a custom font.
I hope this helps! 