Why Computers Can Become Slow When Migrating Between Cybersecurity Products

During cybersecurity migrations, it is common for businesses to replace one endpoint protection platform with another. While this process is generally straightforward, systems can occasionally become extremely slow if remnants of previous security products remain on the device.

We recently experienced this during a migration from SentinelOne to CrowdStrike Falcon. Although SentinelOne had been removed correctly, older security software that had been installed before SentinelOne, specifically Bitdefender, had left behind remnants that began interfering with the new protection platform.

The Symptoms

• All computers across the network became noticeably slow
• The server and workstations experienced performance degradation
• File browsing through Windows Explorer was sluggish
• General system responsiveness was reduced
• No obvious CPU or memory spike was immediately visible

Environment

• Previous security solution: Bitdefender
• Current security solution at the time: SentinelOne
• Migration target: CrowdStrike Falcon
• CrowdStrike protection policy: Phase 3 (Optimal Protection)

What Caused the Problem

Before SentinelOne had been installed on the environment, the systems were protected by Bitdefender. Although Bitdefender had previously been removed, remnants of the software remained on the systems.

These remnants included:

• Residual Bitdefender services
• Cached or temporary Bitdefender components
• Explorer integrations left behind in Windows

SentinelOne had not been significantly affected by these remnants. However, when deploying CrowdStrike in a fully active protection configuration (Phase 3), conflicts began to occur between CrowdStrike and the leftover Bitdefender components still present on the systems.

This conflict caused system performance to degrade across all machines.

How We Diagnosed the Issue

1. Confirmed SentinelOne had been fully removed from the systems
2. Investigated system services and discovered Bitdefender services still present
3. Identified remnants of Bitdefender components still active within Windows
4. Confirmed these remnants were likely conflicting with CrowdStrike’s protection engine

The Resolution

To resolve the issue safely, the following steps were taken:

1. Changed CrowdStrike protection policy to Phase 1 (detect-only mode)
2. Booted affected systems into Safe Mode
3. Ran the official Bitdefender Uninstall Tool to remove all remnants
4. Rebooted systems back into normal Windows mode
5. Confirmed Bitdefender services were no longer present
6. Returned CrowdStrike protection back to Phase 3 (Optimal Protection)
7. Performed system performance testing

The Result

Once the Bitdefender remnants were fully removed and SentinelOne was no longer present, system performance returned to normal. CrowdStrike was able to operate in Phase 3 protection without any further conflicts.

Key Takeaway

When migrating between cybersecurity platforms, it is critical to ensure that all previous endpoint protection software has been completely removed. Even small remnants left behind by older security products can interfere with newer solutions and cause performance issues.

For best results, always use the official vendor removal tools when uninstalling security products, especially when deploying another enterprise-grade endpoint protection platform.