Uploaded June 2026 | Updated September 2026, 1 week ago
An SSD's SLC cache speed is a lot faster than its TLC NAND speed. You may have noticed that your SSD performs very fast but while it is writing large files and folders the speed will slow down. This is because the fast speed if the SLC speed and when the SSD runs out of SLC it will then write direct to the slower TLC.
Factors that will influence the SLC speed compared to the TLC speed and its sustained high speeds are things such as, the capacity of the SSD, how much SLC the SSD has and the type of SLC being used. Each brand of SSD and their different models will also have different results and the type of NAND used will also be a factor.
Even if you have a large capacity SSD that has a lot of SLC, it too will slow down when writing to its TLC. The amount of time that the SSD will sustain its maximum write speed using SLC will also become less the more the capacity of the SSD fills up. In certain instances with certain SSDs, they will effectively have a continuous slow write speed and no fast speed as the SSD's capacity, or available space, has been reduced to a certain point.
You will notice this difference with SLC and TLC on all modern NVMe SSDs and most SATA SSDs. Ironically, when earlier SSDs hit the market many of them did not suffer this problem, as these SSDs were effectively all SLC.
Hopefully this video has helped you to understand why you have noticed that your SSD slows down when it is writing data.
Video chapters:
00:00 Intro
00:31 Explaining the SSD setup
01:23 Showing the fast SLC speed
02:00 Showing the slow TLC speed
02:46 The speed is now below 100MBps
03:25 More things to consider
Zike website: geni.us/ZikeTech
Buy the Zike Z666 from the Zike website and use my discount code David20 for a 20% discount: geni.us/Zike-Z666
Buy the Zike Z666 enclosure on Amazon geni.us/ZikeZ666
Check back soon as I will be doing another SSD build with the Zike Z666 and the 1TB WD SN7100, which is an awesome and fast combination for any 40Gbps connection, USB4 or Thunderbolt 4.
Here's some recommendations for fast NVMe SSDs.
*Samsung 9100 Pro PCIe Gen 5 SSD*
*WARNING - ONLY BUY THIS SSD IF YOU ARE USING A PCIE GEN 5 COMPATIBLE SSD ENCLOSURE*
8TB amzn.to/43WAEK4
4TB amzn.to/4lpGMke
2TB amzn.to/413Jjct
1TB amzn.to/3JcjW1Z
*Other Gen 5 NVMe SSDs* amzn.to/4x7xxwb
*WD_Black SN850X PCIe Gen 4 SSD*
8TB amzn.to/478cVJn
4TB amzn.to/3U7TqsP
2TB amzn.to/3Hb32jC
1TB amzn.to/3He93Mp
*Other Gen 4 NVMe SSDs* geni.us/Gen4SSDs
*Apple Mac Computers*
MacBook Pro amzn.to/4fLL7yJ
MacBook Air amzn.to/4vh13ha
MacBook Neo amzn.to/4uCuVoh
Mac Studio amzn.to/4uCuVoh
Mac mini amzn.to/4aeq04y
iMac amzn.to/3PuKvTI
*Apple Amazon Store* amzn.to/4uDB8QO
*My Amazon global links, using them supports my channel. Thank You👍*
Amazon USA: geni.us/Amazon-USA
Amazon UK: geni.us/Amazon-UK
Amazon Deutschland: geni.us/Amazon-Deutschland
Amazon France: geni.us/Amazon-France
Amazon España: geni.us/Amazon-Espana
Amazon Italia: geni.us/Amazon-Italia
Amazon Canada: geni.us/Amazon-Canada
*AMAZON ASSOCIATE DISCLOSURE:*
I am an Amazon Associate. My Amazon links are Amazon affiliate links. I earn money from qualifying purchases when you use my Amazon affiliate links.
If you found my video super helpful and would like to buy me a coffee: geni.us/CoffeeMe
*CONTACT FOR PRODUCT REVIEWS*
YouTube@DavidHarry.com
DavidHarry.com
I’m David Harry. Thank you very much for watching this video, take care and goodbye now.
Cheers,
Dave.
#SSDspeedtest #MacBookSSD #MacBook #zike #ssd enclosure
An SSD's SLC cache speed is a lot faster than its TLC NAND speed. You may have noticed that your SSD performs very fast but while it is writing large files and folders the speed will slow down. This is because the fast speed if the SLC speed and when the SSD runs out of SLC it will then write direct to the slower TLC.
Factors that will influence the SLC speed compared to the TLC speed and its sustained high speeds are things such as, the capacity of the SSD, how much SLC the SSD has and the type of SLC being used. Each brand of SSD and their different models will also have different results and the type of NAND used will also be a factor.
Even if you have a large capacity SSD that has a lot of SLC, it too will slow down when writing to its TLC. The amount of time that the SSD will sustain its maximum write speed using SLC will also become less the more the capacity of the SSD fills up. In certain instances with certain SSDs, they will effectively have a continuous slow write speed and no fast speed as the SSD's capacity, or available space, has been reduced to a certain point.
You will notice this difference with SLC and TLC on all modern NVMe SSDs and most SATA SSDs. Ironically, when earlier SSDs hit the market many of them did not suffer this problem, as these SSDs were effectively all SLC.
Hopefully this video has helped you to understand why you have noticed that your SSD slows down when it is writing data.
Video chapters:
00:00 Intro
00:31 Explaining the SSD setup
01:23 Showing the fast SLC speed
02:00 Showing the slow TLC speed
02:46 The speed is now below 100MBps
03:25 More things to consider
Zike website: geni.us/ZikeTech
Buy the Zike Z666 from the Zike website and use my discount code David20 for a 20% discount: geni.us/Zike-Z666
Buy the Zike Z666 enclosure on Amazon geni.us/ZikeZ666
Check back soon as I will be doing another SSD build with the Zike Z666 and the 1TB WD SN7100, which is an awesome and fast combination for any 40Gbps connection, USB4 or Thunderbolt 4.
Here's some recommendations for fast NVMe SSDs.
*Samsung 9100 Pro PCIe Gen 5 SSD*
*WARNING - ONLY BUY THIS SSD IF YOU ARE USING A PCIE GEN 5 COMPATIBLE SSD ENCLOSURE*
8TB amzn.to/43WAEK4
4TB amzn.to/4lpGMke
2TB amzn.to/413Jjct
1TB amzn.to/3JcjW1Z
*Other Gen 5 NVMe SSDs* amzn.to/4x7xxwb
*WD_Black SN850X PCIe Gen 4 SSD*
8TB amzn.to/478cVJn
4TB amzn.to/3U7TqsP
2TB amzn.to/3Hb32jC
1TB amzn.to/3He93Mp
*Other Gen 4 NVMe SSDs* geni.us/Gen4SSDs
*Apple Mac Computers*
MacBook Pro amzn.to/4fLL7yJ
MacBook Air amzn.to/4vh13ha
MacBook Neo amzn.to/4uCuVoh
Mac Studio amzn.to/4uCuVoh
Mac mini amzn.to/4aeq04y
iMac amzn.to/3PuKvTI
*Apple Amazon Store* amzn.to/4uDB8QO
*My Amazon global links, using them supports my channel. Thank You👍*
Amazon USA: geni.us/Amazon-USA
Amazon UK: geni.us/Amazon-UK
Amazon Deutschland: geni.us/Amazon-Deutschland
Amazon France: geni.us/Amazon-France
Amazon España: geni.us/Amazon-Espana
Amazon Italia: geni.us/Amazon-Italia
Amazon Canada: geni.us/Amazon-Canada
*AMAZON ASSOCIATE DISCLOSURE:*
I am an Amazon Associate. My Amazon links are Amazon affiliate links. I earn money from qualifying purchases when you use my Amazon affiliate links.
If you found my video super helpful and would like to buy me a coffee: geni.us/CoffeeMe
*CONTACT FOR PRODUCT REVIEWS*
YouTube@DavidHarry.com
DavidHarry.com
I’m David Harry. Thank you very much for watching this video, take care and goodbye now.
Cheers,
Dave.
#SSDspeedtest #MacBookSSD #MacBook #zike #ssd enclosure
