Speed Differences - LAN vs. WIFI to a single HOST

I have a puzzling issue that I could use some insight with.

I have a remote site connected via MPLS 10mb. The site has an L3 switch, an MPLS router, a Firewall for internet, and a single WIFI access point (Ubiquity Unify UAP-PRO running 2 bands).

In the MPLS cloud, many sites are connected, but there are (2) specific sites that have resources used by all sites.

• Site 1 has a CRM app

• Site 2 has all Windows resource apps

When this site connects to the CRM app via LAN, everything is perfect, fast, and without issues.

When this site connects to the CRM app via WIFI, the app connects but it's very slow and sluggish. All Window resources are OK and perfectly fast, and internet access is fine as well.

Flip the client back to LAN and the CRM app speeds up perfectly.

The LAN switch is a Cisco 3560 with ip routing enabled. This is the default gateway for LAN and WIFI clients. WIFI clients get DHCP on the same LAN subnet, not a separate VLAN. Debug shows no issues, no arp pollution, nothing strange at all.

Can anyone offer any insight as to how to figure this out? I'm out of ideas.

Thanks!