Creating a solution > About setting up container fields > Managing performance with thumbnails
 
Managing performance with thumbnails
To speed up the rendering of images in container fields, FileMaker Pro by default generates image thumbnails and caches them in memory.
The container data can be embedded in the field or stored externally. FileMaker Pro encrypts thumbnails that are in secure storage and that are embedded.
You must have full access privileges to set options for thumbnails.
To set thumbnail options:
1. Choose File menu > Manage > Containers.
2. Click the Thumbnails tab.
3. Select or deselect Generate and store thumbnails for images.
This option is selected by default. If you deselect the option, skip to step 5.
4. Choose storage options for thumbnail images.
 
To use
Do this
Temporary storage
Select Temporary storage (the default).
Temporary storage caches in-memory only. Each time the database file is closed, the cache is discarded.
Permanent storage
Select Permanent storage.
Permanent storage caches on-disk in addition to in-memory. The on-disk portion of the cache remains when the database file is closed.
5. Click OK.
Notes 
If generating thumbnails for temporary storage slows performance, change the setting to permanent storage.