VPN Client/VPN Director Issue: web pages slow to load, even on devices not routing through VPN

[dom2114]

Long time Merlin user. Recently upgraded from RT-AC86 to RT-BE86 and am having issues using the VPN client settings.
Please note: the following issue has been replicated using 2 different VPN providers (Private Internet Access, VeePN), and multiple servers with each of these vendors. I do not think it is a provider issue.

VPN Client settings:

• Accept DNS Configuration = Strict
• Redirect internet traffic through tunnel = VPN Director / Guest Network
• Killswitch = Yes

The goal is to just route a single IP address through this VPN. VPN Director setting:

• Local IP = 192.168.1.5
• Interface = OVPN2

My issue:
All devices are noticeably slower loading webpages with these settings.
As soon as I disable the VPN, load times go back to normal.
I also noticed that setting 'Accept DNS Configuration' to Disable seems to fix the page load times as well. Not sure if this means that somehow all DNS requests are being routed through the VPN.
Does anyone have any suggestions on how to fix this? I wasn't experiencing this sluggishness on my old router, but I no longer have access to it to compare/contrast settings.
Would perhaps using x3mrouting produce different results?

Thanks for any suggestions anyone has.

Edit: I performed a factory reset to remove any influence of Entware or other tweaks, and was able to replicate the above issues.