Large data sets, first-time full syncs, or configurations involving Campaign History can take time to complete — sometimes many hours depending on the size of your CRM and the destinations you’re syncing to. 

This article explains why, how to speed up your syncs, and how to test safely without waiting for long-running syncs to finish.

Why First-Time Syncs Take Longer

During the first sync, SyncApps must:

1. Cache all CRM records you intend to sync

2. Index and match each record between systems

3. Store Campaign History or Engagement Data (if selected)

4. Map every field included in your configuration

This means the first sync is naturally the slowest.
Subsequent syncs run dramatically faster.

Real Example

A nonprofit syncing ~291,562 Salesforce Contacts to ActiveCampaign reported that their first sync appeared slow. In this case, the delay was caused by:

• A large data set

• Many mapped fields

• And the selection to sync 30 days of Campaign History, which increases processing time by ~50%

How to Speed Up the First Sync (Best Practices)

1. Turn OFF Campaign Metrics / Campaign History (Step 1)

Campaign History requires one-by-one API calls on every record — which can multiply sync time significantly.

If you have a large database (50k–500k+ contacts), we recommend:

✅ Run your first sync with Campaign Metrics OFF
✅ Turn it ON only after the first sync completes

This alone can reduce the first sync time by half.

2. Test With a New Integration Profile (Fastest Method)

If you need to test mapping or behavior before a long full sync completes:

✅ Create a second integration
✅ Sync from Salesforce only
✅ Leave Campaign Metrics OFF
✅ Apply a filter if you want to test with a subset

This allows you to test quickly without waiting for the full sync to finish.
(This is the recommended approach for most during testing.)

3. Use the Salesforce → Destination-Only Sync for Initial Tests

For extremely large data sets:

✅ Sync from Salesforce only to validate

• Field mapping

• Filtering

• Object behavior

• Record creation

✅ Then run a full bi-directional sync only after confirming everything works.

4. Avoid “Reset Sync Process” Unless Absolutely Necessary

Resetting the sync:

⚠️ Forces SyncApps to reprocess all records again
⚠️ Makes the next sync as long as the first sync
⚠️ Restarts all indexing and API checks

Pro tip:

“Do not hit Reset Sync Process unless necessary as that just makes it take the same amount of time as syncing the first time.”

5. Expect Long Syncs for Large Lists + Campaign History

If your organization sends many campaigns via Constant Contact, ActiveCampaign or Mailchimp, syncing 30 days of history requires:

🔹 Checking each campaign
🔹 Checking each email in each campaign
🔹 Matching against each CRM record

For a database of 300k+ contacts, this may take 24–72 hours, depending on:

• API throughput

• Campaign volume

• Field mapping complexity

We recommend running the first sync over a weekend for large datasets.
(This is the same guidance given in the nonprofit case above.)

How to Test Your Integration Before the First Full Sync

If you need to test behavior or mapping before the initial large sync completes:

Use a duplicate integration (fast)

• Create a new integration

• Sync Salesforce → Destination only

• Turn OFF Campaign Metrics

• Optionally filter to a few records

This avoids the long wait and lets you validate logic immediately.

Why not “filter inside the main sync”?

Even if you filter to one email address, SyncApps must still cache and index your entire CRM the first time — because CRM systems don’t allow partial-data caching on the first sync.

So a “subset test” inside the main integration still requires the full dataset to be cached.

Common Questions

“Why does filtering not speed up the first sync?”

Because the platform must index all CRM records on the first run, even if only one record matches your filter.

“Why do subsequent syncs run faster?”

Because only changes are synced after the first full data cache.

“Can I run another integration while one is syncing?”

Yes — This allows parallel testing.

✅ Summary of Best Practices

For Faster First Syncs

• ✅ Turn OFF Campaign Metrics

• ✅ Reduce mapped fields if possible

• ✅ Run the first sync over a weekend for large data sets

• ✅ Do NOT Reset the Sync unless needed

For Faster Testing

• ✅ Use a second integration profile

• ✅ Sync from CRM only

• ✅ Use filters in the test integration, not the main one

Need help optimizing a long sync?

Our team can review your integration setup and recommend:
✅ optimal filtering
✅ field mapping strategies
✅ Campaign History options
✅ parallel testing workflows

Book a sync review: https://www.cazoomi.com/services/#schedule