For the F800, a Capsense conversion takes 40uS per channel.
Allowing the MCU to enter Suspend Mode during the Capsense conversion pushes the overall current consumption lower.
To achieve that, enable the CS0 comparator and set the CS0TH to 0x0000.
This allows the MCU to wake up from Suspend Mode after every Capsense conversion due to a greater-than comparator interrupt, since the CS0D (capsense result) will always be more than CS0TH (0x0000).

After the C8051F800 MCU wakes up from Suspend Mode due to the Capsense greater-than comparator interrupt, the CS0CN register can only be cleared after 2 system clock cycles.
Code snippet is shown below:

         CS0CN |= 0x10;           // Start conversion
         OSCICN |= 0x20;         // Place MCU in SUSPEND Mode, save current
         NOP();                          // 2 NOPs required after SUSPEND Mode
         NOP();                          // otherwise, cannot clear CS0 Conversion Complete interrupt flag
                                               // and CS0 Greater Than interrupt flag

         CS0CN &= ~0x21;       // Clear CS0 Greater than interrupt flag and conversion complete flag


Alternatively, the flags can be cleared before starting a conversion.
Code snippet is shown below:
         CS0CN &= ~0x21;       // Clear CS0 Greater than interrupt flag and conversion complete flag
         CS0CN |= 0x10;           // Start conversion
         OSCICN |= 0x20;         // Place MCU in SUSPEND Mode, save current

This issue does not occur in the F700 MCU due to the need for a SFR page change for the F700 MCU.
Code snippet for the F700 is shown below:
         CS0CN |= 0x10;            // Start conversion
    
         SFRPAGE = CONFIG_PAGE;
         OSCICN |= 0x20;                       // Place MCU in suspend mode
         SFRPAGE = LEGACY_PAGE;  // This involves a MOV instruction which takes up 2 machine cycles

         CS0CN &= ~0x21;                    // Clear CS0 Greater than interrupt flag and conversion complete flag