Samsung has just updated its launcher app in the Google Play Store and the Galaxy Apps Store, and under the changelog it notes that this update has fixed the lag when swiping up and down to go from the home screen to the app drawer. However, according to reports of those that have already downloaded the update, it hasn't fixed the lag. It's a very small hint of lag on the Galaxy S8 and Galaxy S8 Plus, so small that many won't even notice it's there. So it's not a huge deal, but it does definitely appear that Samsung has not yet fixed it, completely.
This update brings the home launcher (interestingly still named "Samsung Touchwiz Home" even though Samsung has dropped the Touchwiz name as of the Galaxy S8/S8 Plus) to version 6.1.09.2. The update is available in both stores, so you can download it from whichever one you'd like. The update does also fix some other performance issues, although they aren't called out like the lag issue with the swiping for the app drawer though. There is also an information screen available in the Samsung Touchwiz Home app here. So it's not a huge update, but it does make some changes that should improve the user experience, unfortunately there are no new features coming into this update for the launcher.
The launcher that comes on the Galaxy S8 and Galaxy S8 Plus is pretty nice, and many people like it. But if the lagging in swiping from the home screen to apps is to much, then users are always able to download a third-party launcher from the Google Play Store. There are plenty available, and many are lighterweight (which means less resources being used, and that translates to better performance and battery life) as well as offering new features. There are things like Nova Launcher, Action Launcher and many others, which do bring in some pretty nifty features from Google's Pixel smartphones. You can download the update for the Samsung Touchwiz Home app via the Google Play Store link below, or head over to the Galaxy Apps Store and grab it.