Bug:Route download performance degradation in 202405 (from FIB Suppression)

[mike-dubrovsky]

Is it platform specific

generic

Importance or Severity

Critical

Description of the bug

Note: Could you please assign the bug to me ; i have fix ready for review.

SONiC route download speed degraded (from around 4K/sec to 2K/sec) after BGP prefix suppression (bgp suppress-fib-pending) was introduced. The root cause is that RouteOrch::publishRouteState() unconditionally writes to APPL_STATE_DB and sends a Redis pub/sub notification on every route add/remove — even when FIB suppression is disabled and no consumer needs the data.

Impact
orchagent is the bottleneck for route programming; the overhead directly degrades route download speed
The majority of deployments do not enable suppression, so most users pay the cost for no benefit

Steps to Reproduce

compare route download speed in 202405 and any prior release.

Actual Behavior and Expected Behavior

publishRouteState() should be no-op when FIB suppression is disabled

Relevant log output

Output of show version, show techsupport

Attach files (if any)

Note: Could you please assign the bug to me ; i am preparing PRs for the review.
sonic-net/sonic-swss#4333
#26151
sonic-net/sonic-utilities#4361
sonic-net/sonic-mgmt#22916