Can you look at the disassembly and see if the accesses are single instruction?
I'm using the arduino IDE, I don't know how to do that with this.
The Arduino IDE actually makes it relatively simple to do this. Make a trivial change to your source code -- maybe add and delete a character and then hit the "check"/"compile" button. IN the panel at the bottom (maybe make it bigger) you'll see a line like the following, with the first (very long) "word" ending in gcc and the path to your eventual executable binary file in the middle (here Blink.ino.elf) after a "-o". Or for certain targets the gcc might be ld instead.
/home/bruce/software/arduino-1.8.10/hardware/teensy/../tools/arm/bin/arm-none-eabi-gcc -O1 -Wl,--gc-sections,--relax -T/home/bruce/software/arduino-1.8.10/hardware/teensy/avr/cores/teensy4/imxrt1062.ld -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -o /tmp/arduino_build_829669/Blink.ino.elf /tmp/arduino_build_829669/sketch/Blink.ino.cpp.o /tmp/arduino_build_829669/core/core.a -L/tmp/arduino_build_829669 -larm_cortexM7lfsp_math -lm -lstdc++
Open a terminal window (from your OS, nothing to do with gcc) and copy and paste the bit with gcc or ld and the output file. Don't try to run it yet!
/home/bruce/software/arduino-1.8.10/hardware/teensy/../tools/arm/bin/arm-none-eabi-gcc /tmp/arduino_build_829669/Blink.ino.elf
Now just replace the "gcc" bit by "objdump -d":
/home/bruce/software/arduino-1.8.10/hardware/teensy/../tools/arm/bin/arm-none-eabi-objdump -d /tmp/arduino_build_829669/Blink.ino.elf
You can run that.
If you can't scroll your terminal window backwards then you might want to put " | more" (or " | less") on the end, or redirect the output to a file with " >/home/bruce/myDisassembly.txt" or whatever other location or name you want. (Your name probably isn't Bruce...)
If the compiler is gcc then you can get an assembly language listing by instead finding the line that compiled your code ("Blink.ino.cpp") to an object file ("-o .../Blink.ino.cpp.o"). You can just copy and paste the whole line into your console/terminal window and re-run it. If you add to the end " -g -Wa,-adhl" then you'll get a listing printed to the terminal with the original lines of C code, the generated assembly language, and the binary (hex) code for the instructions.