Answer:

The "Interval" times on the Monitor page should be 10 seconds or close to it, and the "Sample Times" should be less than 1 second

Here is an example where Foxhound is taking longer than normal to gather samples:

Heartbeat, Sample Samples Interval Times 5:40:56 AM 14.3s .1s / 13.2s 5:40:42 AM 12.3s .1s / 11.3s 5:40:30 AM 15.9s .1s / 14.9s

Have a look at the "SPs are OK:" field in the Monitor Status Area at the top of the Monitor page.

If it is showing SPs are OK: NNN or something other than SPs are OK: YYY, try to ensure that the Foxhound's three stored procedures for gathering performance statistics are installed on the target database; see Help - Introduction - Connecting to Target Databases.