If you want to avoid having to create 4 or 5 columns for single field (and multiplying that by 30 in your case), there is a more direct approach using a JavaScript column.
It wasn’t mentioned in the previous answer because it’s slightly outside the scope of no-code logic obviously. However I believe it makes sense here.
JavaScript column
Instead of the steps described ealier, siply add a JavaScript column and configure it like this:
Here is the code:
let value = p1;
let decimals = p2;
return value.toFixed(decimals)
It would also work with just return p1.toFixed(p2) - the classic readability versus conciseness dilemma 
This code uses the value of p1 (which corresponds to Value in the screenshot) and returns it with the number of decimals specified in the Number of decimals column - the p2 parameter. Note that when the number of decimals is not filled (e.g. in the third row), the default behaviour is to remove all decimals.
A tip when using JS
Assuming you go down this path, here’s a useful tip:
- Create a Template column to store the code directly in the table
- Then, instead of writing the actual code in the JavaScript column, reference the template column we just created:
Since you’ll be applying the same function across 30 columns, ithis approach makes your logic easier to maintain, more scalable and less prone to typos 
Ideally, this Template column should be stored in the Users table - this way , you’ll be able to reuse the same function in any other table within your app.
Very helpful when you’re applying the same logic in multiple areas (I saw this in one of Marco Volpato’s tutorials - brilliant 
)
Performances
It’s very difficult to provide feedback on performance-related questions. It depends on many factors, even though there are some generally valid tips - such as avoiding If → Then → Else columns with many conditions.
One thing that’s easy to do, however, is to activate a feature called Analyse Table Performance, available under Settings → Developper Tools
You can now run the analysis on your table and identify possible bottlenecks:
Hope this is what you were looking for! 
