I also wrote a benchmark for different MCUs, both AVRs and ARMs.
The benchmark test peforms low- and high-level tests for integers, floats, doubles, bitshift, random, sort, matrix algebra, GPIO r/w, and graphics.
The test will run even without having attached a TFT, you may keep the #included Adafruit libs or optionally substitute them by proprietary ones.
Update: the test for Raspberry Pi now also has been completed.
As AVRs don't feature 64 bit doubles, the 32bit float test is performed twice, without issueing penalty points though (which admittedly is not fair to the ARM boards 
)
( ... to be continued ... )
test design:
0 int_Add 50,000,000 int +,- plus counter
1 int_Mult 10,000,000 int *,/ plus counter
2 fp32_ops 2,500,000 fp32 mult, transc. plus counter
3 fp64_ops 2,500,000 fp64 mult, transc. plus counter (if N/A: 32bit)
4 randomize 2,500,000 Mersenne PRNG (+ * & ^ << >>)
5 matrx_algb 150,000 2D Matrix algebra (mult, det)
6 arr_sort 1500 shellsort of random array[500]
7 GPIO toggle 6,000,000 toggle GPIO r/w plus counter
8 Graphics 10*8 textlines + 10*8 shapes + 20 clrscr
.
Vergleichswerte (update: auch für Raspi jetzt komplett durchgeführt):
Arduino MEGA + ILI9225 + Karlson UTFT + Arduino GPIO-r/w
0 90244 int_Add
1 237402 int_Mult
2 163613 fp32_ops(float)
3 163613 fp32_ops(float=double)
4 158567 randomize
5 46085 matrx_algb
6 23052 arr_sort
7 41569 GPIO toggle
8 62109 Graphics
runtime ges.: 986254
benchmark: 51
Arduino MEGA + ILI9225 + Karlson UTFT + Register bitRead/Write
0 90238 int_Add
1 237387 int_Mult
2 163602 fp32_ops (float)
3 163602 fp32_ops (float=double)
4 158557 randomize
5 45396 matrx_algb
6 23051 arr_sort
7 4528 GPIO_toggle bit r/w
8 62106 Graphics
runtime ges.: 948467
benchmark: 53
Arduino MEGA + adafruit_ILI9341 Hardware-SPI Arduino GPIO r/w
0 90244 int_Add
1 237401 int_Mult
2 163612 fp32_ops (float)
3 163612 fp32_ops (float=double)
4 158725 randomize
5 46079 matrx_algb
6 23051 arr_sort
7 41947 GPIO toggle
8 6915 Graphics
runtime ges.: 931586
benchmark: 54
Arduino/Adafruit M0 + adafruit_ILI9341 Hardware-SPI
0 7746 int_Add
1 15795 int_Mult
2 89054 fp32_ops
3 199888 fp64_ops(double)
4 17675 randomize
5 18650 matrx_algb
6 6328 arr_sort
7 9944 GPIO_toggle
8 6752 Graphics
runtime ges.: 371832
benchmark: 134
Arduino DUE + adafruit_ILI9341 Hardware-SPI
0 4111 int_Add
1 1389 int_Mult
2 29124 fp32_ops(float)
3 57225 fp64_ops(double)
4 3853 randomize
5 4669 matrx_algb
6 2832 arr_sort
7 11859 GPIO_toggle
8 6142 Graphics
runtime ges.: 121204
benchmark: 413
Arduino/Adafruit M4 + adafruit_HX8357 Hardware-SPI
0 2253 int_Add
1 872 int_Mult
2 2773 fp32_ops (float)
3 24455 fp64_ops (double)
4 1680 randomize
5 1962 matrx_algb
6 1553 arr_sort
7 2395 GPIO_toggle
8 4600 Graphics
runtime ges.: 39864
benchmark: 1254
Arduino/Adafruit ESP32 + adafruit_HX8357 Hardware-SPI
0 2308 int_Add
1 592 int_Mult
2 1318 fp32_ops
3 14528 fp64_ops
4 825 randomize
5 1101 matrx_algb
6 687 arr_sort
7 972 GPIO_toggle
8 3053 Graphics
runtime ges.: 25384
benchmark: 1969
Raspberry Pi:
Raspi 2 (v1): 4x 900MHz, GPU 400MHz, no CPU overclock, full-HD, openVG:
0 384 int_Add
1 439 int_Mult
2 346 fp32_ops(float)
3 441 fp64_ops(double)
4 399 randomize
5 173 matrx_algb
6 508 arr_sort
7 823 GPIO_toggle
8 2632 graphics
runtime ges.: 6145
benchmark: 8137
edit: updated for
Arduino/Adafruit Feather ESP32
Ardubench_22_ILI9341_Adafruit.zip (4.88 KB)