Consistent FPS Drop KSEA-CYVR Corridor

I’ve consistently experienced FPS drop within the region from KSEA to CYVR, from departure at KSEA to arrival at CYVR, regardless of scenery setup at High or Ultra. I notice this flying the default TBM 930, default Cessna Caravan and PMDG 737-800, even in good, almost cloudless weather. I’m puzzled since my system is fairly robust (see below) and performs well in other graphics-heavy areas such as at KJFK, KORD, EGLL, etc. Any thoughts, comments, support suggestions?

Thanks in advance,
Elmo A

Operating System: Microsoft Windows 11 Home
Chassis: Corsair 465x Chassis with Corsair SP120 RGB fan package
Mainboard: Gigabyte Z490 Aorus Ultra Mainboard
Processor: Intel Core i7-10700K (5.1GHz Max Boost Clock) 8-Cores
CPU Cooler: Corsair H100i RGB XT 240mm Liquid CPU Cooler
System Memory: 32GB DDR4 3200MHz RGB SDRAM
Graphics Card: 12GB GeForce RTX 4070 Graphics Card
Power Supply: EVGA 1000W Gold Rated Power Supply
Storage Drive: 2TB WD Black NVMe Solid State Storage Drive
Network Connection: Wired Ethernet + 802.11 WiFi + Bluetooth