HP EliteBook 840 G7 still takes ~40–45 seconds to boot after a clean Windows 11 install

I have an HP EliteBook 840 G7 with an Intel NVMe SSD (SSDPEMKF512G8, 512 GB).

I recently bought a refurbished HP EliteBook 840 G7 from Refurbed. The laptop works normally otherwise, but its boot time seems unusually long.

The computer had this slow boot problem before reinstalling Windows, and the problem is reproducible after a completely clean installation.

Current boot times are approximately:

Cold boot to login screen: 39 seconds
Restart to login screen: 45 seconds
Task Manager “Last BIOS time”: 12.3 seconds

To rule out the existing Windows installation, I completely wiped the internal SSD, including the EFI, MSR, Windows and recovery partitions, and performed a clean installation of Windows 11 25H2 from an official Microsoft ISO. Windows recreated all partitions from scratch.

The boot time remained essentially unchanged after the clean installation.

BIOS Fast Boot is enabled and Startup Delay is set to 0 seconds. The BIOS version is HP S70 01.25.00 (2026-06-13).

The SSD reports Healthy / OK in Windows. WinSAT results:

Disk Random 16.0 Read: 606.20 MB/s
Disk Sequential 64.0 Read: 2083.41 MB/s
Disk Sequential 64.0 Write: 1351.38 MB/s
95th percentile latency: 0.151 ms
Maximum latency: 0.823 ms

Windows Diagnostics-Performance (Event IDs 100/110) shows approximately:

BootSmssInitTime: 12563 ms
Session0InitDuration: 8430 ms
BootPNPInitDuration: 2736 ms
SystemPNPInitDuration: 581 ms

SMSS/Session 0 initialization therefore seems to account for a significant part of the delay.

What could cause SMSS/Session 0 initialization to take this long on a completely clean Windows installation? Is there a good way to identify exactly which driver, device or service SMSS is waiting for during boot?

Since the same behavior occurred both before and after wiping the SSD and reinstalling Windows from scratch, I am particularly interested in whether this points to a driver/firmware issue or a hardware device that is slow to initialize.