gRPC listchannels & listnodes performance

[michael1011]

Getting all nodes or channels CLN has gossip for via the gRPC interface is really slow. Calling listchannels via gRPC takes a minute while the CPU usage of the gRPC plugin spikes to 100% on one core

It is definitely not a problem with my CLN installation or my machine because the RPC socket socket is quick:

time lightning-cli listchannels | jq .channels > /dev/null

real    0m4.508s
user    0m2.125s
sys     0m0.273s

getinfo output

{
   "id": "02ead25af6e0271c5167d6fd05545d2d538995ce3e16ad780a1010fc4e91522202",
   "alias": "LOUDGOPHER",
   "color": "02ead2",
   "num_peers": 0,
   "num_pending_channels": 0,
   "num_active_channels": 0,
   "num_inactive_channels": 0,
   "address": [],
   "binding": [
      {
         "type": "ipv4",
         "address": "0.0.0.0",
         "port": 9745
      }
   ],
   "version": "v24.11-28-gdac505d",
   "blockheight": 878642,
   "network": "bitcoin",
   "fees_collected_msat": 0,
   "lightning-dir": "/home/michael/.lightning/bitcoin",
   "our_features": {
      "init": "08a0880a8a59a1",
      "node": "88a0880a8a59a1",
      "channel": "",
      "invoice": "02000002024100"
   }
}