Thank you for your post.
At what point do you see the system slowing down? Are clients printing reports of a table where other clients are editing records? Is there any exporting of records while others are editing? That is, is there any activity occurring that affects the entire database file while others are adding/editing records? I need more information.
A layout is just a way to display information. If the active and archive data are in separate tables, then you will need to duplicate the layout, and then change the Layout Setup and change "Show records from" to the appropriate table. Is there any reason why you didn't want to duplicate the layout?
I don't know of a way to make a layout switch table references "on the fly", but....
26,000 jobs doesn't sound like all that large a number of records. Just for comparison, one of my databases currently stores nearly 185,000 invoice records with 344,000 related line item records.
This file is hosted over the LAN by filemaker server 10, though a year ago, it was hosted by filemaker server 5.
You might want to take a look at your database design for possible bottle necks that could be removed to improve performance.
Typical issues that slow a Filemaker system down are:
Searching and/or sorting on an unstored or unindexed field.
Summary or calculation fields with aggregate functions that summarize large numbers of records.
There are ways that denormalize some of your data in ways that reduce the total number of cacluations needed to compute certain summaries. Sometimes that compromise is needed in order to avoid unacceptable delays though such changes need to be looked at very, very carefully first.