>On the form only records of one organisation should be
>displayed. The user is able to select the organisation
>with a command button. I have set a filter like this:
>organisation = '001'
>
>I have also an index on organisation to optimize the filter.
>But it is still very slow:
>
>e.g. Organisation '001' 150000 records
> Organisation '002' 250 records
>
>It seems that in the case of organisation '002' all records
>were read -> takes 70 seconds to move from the first to the
>last record.
>
>Without a filter it is quite fast.
>
>Any suggestions?

Are you having any relations involved?

If you work with SET DELETE ON, do you have a tag on DELETED()?