From what I see right now I can give such advice:
- Optimize images with https://squoosh.app/ for example https://consolezone.pl/wp-content/uploads/re.jpg can be optimized from 490kb to 188kb with mozJpeg 0.75 ratio (you need to adjust ratio for images according to their look and feel, 0.85 is usually quite enough). Also for JPG sometimes image of 2000×2000 px and with 0.75 compression will look better and be less in size then 1000×1000 with same 0.75 ratio, so give it a try, obviously for retina devices if you know that image will be displayed at maximum size of 1000px wide just double it and compress with good ratio and it will be both good quality looking and light in size.
- Enable lazy loading of images, you can try https://wordpress.org/plugins/rocket-lazy-load/ or some other lazy loading plugin.
- In addition about images – to make pagespeedinsights happy and users with browsers supporting webp you can install plugin which will enable webp image format support https://wordpress.org/plugins/webp-express/
- Another important part for your website is -> your theme and plugins load a lot of separate css\js, i see that W3C Total Cache plugin is installed already, so you need to experiment with options of combining js and combining css, some detailed tutorial here https://code.tutsplus.com/articles/configuring-w3-total-cache-advanced-minification-settings–wp-31043
Please make a backup before trying any of these advice! and make sure you can rollback (so backup-restore actually works).
Images lazyloading plugin replaces img tags on the fly so if something will go wrong – just disable it, and reset cache.
For WebpExpress plugin set up it to generate webp version of images in separate folder so if you’ll disable it for some reason later you’ll be able to cleanup files easier.
Also check PHP version on your host, if you are running php 5.6 or earlier, just switch to PHP 7.1 or 7.2 will dramatically increase site’s performance, and TTFB (time to first byte) will be lower. You can try to switch to PHP 7.3 as well but there can be incompatibilities in some plugin’s code so anyway do a test before, running a site locally with new PHP version and define('WP_DEBUG', true) to see errors\warnings\notices if they happen.