The terms "High Speed Peripherals" and "Low Speed Peripherals" can be found in TRM 001-85634 Rev. *B, Table 11-2. Available Peripherals.
What is the definition of "High Speed Peripherals" and "Low Speed Peripherals"?
Here is the definition for high/low speed peripherals-
High peed peripherals- Peripherals that operate from high frequency clock (HFCLK)
Low speed peripherals- Peripherals that operate from low frequency clock (ILO)
In clock settings window (click edit clock in .cydwr tab), you can see high frequency and low frequency clocks and their frequency range.
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