I’ve got a trainee programmer using a budget laptop (cpu might be an i3) and I’m tired of watching how slow rebuilds are compared to my three year old Mac book Air.
In retrospect, I should have bought him a better machine but before I buy a new one, I’m wondering if I can buy an external SSD and boot/ run from there and get some noticeable performance boosts? I don’t want to install it internally for various reasons.
Tia
Yes. I changed my HDD to SSD and felt huge difference. My laptop is Macbook Pro 2011 with i7. Although it had a i7 CPU, build time was very slow.
OK cool. Sorry I’m a bit of a dumbarse with hardware but do you know if having the SSD as external (maybe connected via USB 3) would negate the benefits or is USB not a bottle neck?
You didn’t say if yours was externally installed or not.
Cheers
USB 3.0 supports speeds up to 5 Gbit/s (625 MB/s)
Actually, most SSDs are “the bottleneck” here.
Yeah I think slow build times on HDD’s are not because of bandwidth limitation (a HDD can still get around 200-250MB/s read with sequential data), but because of response time. During building it has to access a lot of very small files, for each file it can take around 10ms to start reading, on an SSD this is pretty much negligible. If it has to access 1000 files that already amounts to 10 seconds in total just for seeking time.
So yeah, an ssd, even an external one, will probably speed up a lot.
Another option is to use a ramdisk. It’s software with which you create a new drive that sits entirely in your RAM and thus is very fast. For me personally it didn’t speed up build times much from the internal ssd, but I’m sure the difference with an hdd will be very noticeable.
I’ve just done some testing using Blackmagic Disk Speed Test on my MacBook Pro 2012 model with macOS Sierra beta 7:
External USB (3.0) disk:
Read: ~75MB/s
Write: ~75MB/s
Internal 7200 HDD WD7500BPKT-00PK4T0 (SATA6 capable controller but disk negotiated SATA3 - up to 300MB/s):
Read: unable to benchmark system disk but declared at 160MB/s
Write: unable to benchmark system disk but declared at 160MB/s (?)
I have to say that building a fairly moderate Meteor app was painfully slow.
Internal OWC Mercury EXTREME Pro 6G SSD (SATA6 in CD bay):
Read: ~450MB/s
Write: ~250MB/s
Building/running the same Meteor app off of it becomes bearable, but…
Internal OWC Mercury EXTREME Pro 6G SSD + another one in the CD bay, both in RAID0 (stripe):
Read: ~900MB/s
Write: ~500MB/s
…still not beating ~2,500MB/s in latest MBPs of course, but makes building/running the same app quite comfortable 
NOTE: If you go for the latest case, make sure you do regular backups because failing only one SSD will destroy all your data!
2500mbps… wtf… cant wait for new gen MBPs
one of the best you can get
Make the SSD internal instead of external to increase build speed.