Here are speed benchmarks for some of the most commonly used cryptographic algorithms

Precomputation means using a table of 16 precomputed powers of each fixed base to speed up exponentiation.

https://www.cryptopp.com/benchmarks.html 

 

LTC1595 - Serial 16-Bit Multiplying DACs

Description

The LTC®1595/LTC1596/LTC1596-1 are serial input, 16‑bit multiplying current output DACs. The LTC1595 is pin and hardware compatible with the 12-bit DAC8043 and comes in 8-pin PDIP and SO packages. The LTC1596 is pin and hardware compatible with the 12-bit DAC8143/AD7543 and comes in the 16-pin SO wide package.
Both are specified over the industrial temperature range. Sensitivity of INL to op amp V_OS is reduced by five times compared to the industry standard 12-bit DACs, so most systems can be easily upgraded to true 16-bit resolution and linearity without requiring more precise op amps.
These DACs include an internal deglitching circuit that reduces the glitch impulse by more than ten times to less than 1nV-s typ.
The DACs have a clear input and a power-on reset. The LTC1595 and LTC1596 reset to zero-scale. The LTC1596‑1 is a version of the LTC1596 that resets to mid-scale.

http://www.linear.com/product/LTC1595

SiTime's all-silicon MEMS resonators are at the core of SiTime's MEMS-based silicon oscillator and clock generator products. These extremely stable and ultra-robust resonators, based on SiTime’s groundbreaking TempFlat MEMS technology, are manufactured using standard CMOS process equipment in semiconductor fabs, using silicon on insulator (SOI) wafers. The resonators are vacuum-sealed in silicon and can be packaged in cost-effective plastic packages. More on how SiTime's resonators are manufactured.

https://www.sitime.com/technology/mems-resonators 

setClockDivider()

Description

This function should not be used in new projects. Use SPISettings with SPI.beginTransaction() to configure SPI parameters.
Sets the SPI clock divider relative to the system clock. On AVR based boards, the dividers available are 2, 4, 8, 16, 32, 64 or 128. The default setting is SPI_CLOCK_DIV4, which sets the SPI clock to one-quarter the frequency of the system clock (4 Mhz for the boards at 16 MHz).

https://www.arduino.cc/en/Reference/SPISetClockDivider