Website very slow while wpematico creating posts

Hi ! I use plugin for around a year. Works great but i have a problem which maybe is not related with plugin but however i ask for help.
I have set plugin to create posts from feeds every 1 hour.
So while executing the job , the visitors are not able to open a page .The browser just waiting around 20-30 seconds for a page to open.
I use also a cron to visit pages after they have created so to cache them .
Pages start to work good after they are cached again.
Maybe this is related to caching i am not sure, but if i disable cache , then problem is more bad and pages are always slow.
However problem is bigger while feed job is running.
Is it any solution to run in background and give priority to visitors ?
Currently, my page works like this .For 50 minutes per hour, pages works fast.But for 10 minutes every 1 hour, pages run very slow.
I search for a solution. Thank you !