If page load speed is an issue it might be worth looking at your site using Googles Page speed insights tool. This will help you get a picture for how you can improve the speed of you page for your users.
You can change your links manually to hardcoded affiliate links. This will improve your page load speed however the downsides is that is may make keeping your content up to date more challenging.
Alternatively you can make use of the link wrapper tool if you have developer resources to automate the update.
Skimlinks is unable to update the urls on your behalf however we would recommend that you consider if there are other areas you may be able to get the same or more improvement in page speed in other areas.