Hi Bruno,

Indexes make your write operations (create, update, delete) slower and querying faster, if they leverage on those attributes, by the same order, for joining, filtering and sorting.

Being that said, as a rule of thumb, you want foreign keys indexed because by definition they are going to be used on joins and those are automatically created by OutSystems (the ones starting with AutoIndex). Other than that, you want the minimum possible indexes, except if you need them, like on the situations I mentioned before.

Anyway, a performance loss in the table might happen by several reasons.

Do you have a heavy query?
Is it optimized (using tops, retrieving the least amount of data, using SQL most performant operations, etc.)?
Has the amount of data grown so much? If so, have you thought about archiving?

It's impossible to conclude from your image that one index is the root cause for the loss of performance you are facing.

Kind Regards,
João