As a fact, installing more apps will likely have a negative effect on page speed since there are more resources that need to load. However, all you need is to consider the pros and cons of having your popup setting ups. Usually one pop-up increases page speed by 1-2 seconds, but if this boosts more sales and conversions then slightly increasing the page speed is not a big deal.
In case you’re having the popup display right away, we recommend waiting about 30 seconds to give the page time to load as well as for the user to move around before displaying the popup.
You could also look for other areas in your store that could be optimized to try and offset that increase in page speed.
These are some main points of optimization for Shopify sites:
Image optimization: Images are heavy, making image compression and changing image size on server key tactics for a faster site.
Reducing server requests: Try to set up "Lazy loading" in Shopify partners and clear unnecessary apps to reduce the number of files loaded on your page and make it load faster.
Technical optimizations: If you have your own developer, fixing server errors, gzip compression, syncing non-essential scripts and server configuration should be checked on a monthly basis.
Test your funnel from all devices, use A/B testing to see if there are any optimization opportunities to target. Take this chance to optimize your site now and enjoy a long term boost in your key metrics.