Restoring 5000pods takes long time (more than 10 hours)

Description of problem:

testing backup&restore of 5000pods in a single namespace.

pods were created on ceph-rbd and using CSI plugin.

backup 5K pods - 9Hrs
restore 5K pods - 10.5Hrs

Version-Release number of selected component (if applicable):

Scale-Env: cloud33 (3 masters & 12 workers)

OCP: 4.10.21
OADP: 1.1.0-53 (iib 285237)

How reproducible:

Steps to Reproduce:
1. Create single namespace with 5K pods over ceph-rbd (PV size - 32MiB)
2. Create CSI backup 
3. Delete the namespace
4. Restore the namespace

Actual results:

restore finished after 10.5 Hrs

Expected results:

restore should finished after ~5Hrs

Additional info:

DPA

[root@f07-h28-000-r640 07Aug22_10-05-45]# oc get dpa example-velero -nopenshift-adp -oyaml
apiVersion: oadp.openshift.io/v1alpha1
kind: DataProtectionApplication
metadata:
  creationTimestamp: "2022-08-01T20:49:31Z"
  generation: 1
  name: example-velero
  namespace: openshift-adp
  resourceVersion: "52822724"
  uid: 7675350b-463a-4e13-9992-3ed1f5f04e7b
spec:
  backupLocations:
  - velero:
      config:
        insecureSkipTLSVerify: "true"
        profile: noobaa
        region: noobaa
        s3ForcePathStyle: "true"
        s3Url: https://s3-openshift-storage.apps.oadp305.cloud33mpqe.com
      credential:
        key: cloud
        name: cloud-credentials
      default: true
      objectStorage:
        bucket: oadp-bucket
        prefix: velero
      provider: aws
  configuration:
    restic:
      enable: true
      podConfig:
        resourceAllocations:
          limits:
            cpu: 2
            memory: 32768Mi
          requests:
            cpu: 1
            memory: 16384Mi
      timeout: 900m
    velero:
      defaultPlugins:
      - openshift
      - aws
      - csi
      podConfig:
        resourceAllocations:
          limits:
            cpu: 4
            memory: 32768Mi
          requests:
            cpu: 2
            memory: 16384Mi
status:
  conditions:
  - lastTransitionTime: "2022-08-01T20:49:31Z"
    message: Reconcile complete
    reason: Complete
    status: "True"
    type: Reconciled
[root@f07-h28-000-r640 07Aug22_10-05-45]#

{+}Backup
{+}[root@f07-h28-000-r640 07Aug22_10-05-45]# oc get backup backup-csi-ocs-5000pods -nopenshift-adp -oyaml
apiVersion: velero.io/v1
kind: Backup
metadata:
  annotations:
    velero.io/source-cluster-k8s-gitversion: v1.23.5+3afdacb
    velero.io/source-cluster-k8s-major-version: "1"
    velero.io/source-cluster-k8s-minor-version: "23"
  creationTimestamp: "2022-08-04T03:38:14Z"
  generation: 5030
  labels:
    velero.io/storage-location: example-velero-1
  name: backup-csi-ocs-5000pods
  namespace: openshift-adp
  resourceVersion: "70652310"
  uid: a23d35c1-5d97-4c56-8d51-8331ffd1451e
spec:
  defaultVolumesToRestic: false
  hooks: {}
  includedNamespaces:
  - busybox-perf-single-ns-5000-pods
  metadata: {}
  storageLocation: example-velero-1
  ttl: 720h0m0s
status:
  completionTimestamp: "2022-08-04T12:42:16Z"
  csiVolumeSnapshotsAttempted: 5000
  csiVolumeSnapshotsCompleted: 5000
  expiration: "2022-09-03T03:38:14Z"
  formatVersion: 1.1.0
  phase: Completed
  progress:
    itemsBackedUp: 64965
    totalItems: 64965
  startTimestamp: "2022-08-04T03:38:14Z"
  version: 1

Restore
[root@f07-h28-000-r640 07Aug22_10-05-45]# oc get restore restore-csi-ocs-5000pods -nopenshift-adp -oyaml
apiVersion: velero.io/v1
kind: Restore
metadata:
  creationTimestamp: "2022-08-04T15:18:39Z"
  generation: 8234
  name: restore-csi-ocs-5000pods
  namespace: openshift-adp
  resourceVersion: "74633507"
  uid: aff03c02-51f5-4553-bd61-d20b0a3e7ddc
spec:
  backupName: backup-csi-ocs-5000pods
  excludedResources:
  - nodes
  - events
  - events.events.k8s.io
  - backups.velero.io
  - restores.velero.io
  - resticrepositories.velero.io
  hooks: {}
  includedNamespaces:
  - '*'
status:
  completionTimestamp: "2022-08-05T01:49:11Z"
  phase: Completed
  progress:
    itemsRestored: 55026
    totalItems: 55026
  startTimestamp: "2022-08-04T15:18:39Z"
  warnings: 5004

{+}
{}{+}