Hello @Klipoorbellennl ,
To tell the story short - your store speed is mostly dependent on loading heavy files (images/videos) and/or adding 3rd party scripts that could remain after removing the apps. I would mostly look for those extra scripts, the Shopify expert will need only a couple of hours to identify what is left.
My team has huge experience in speed optimization. There are several non-trivial aspects to consider.
Please, get in touch if you need any assistance.
Best regards,
Anastasia