Bitcoin-QT: which external memory (connected via USB2.0 + TrueCrypt) would work? Background
I have Bitcoin-QT 0.9.3 (zip version). bitcoin-qt.exe sits on the internal HDD of my laptop. All of the other stuff (blockchain, wallet,...) on a 128GB USB drive, fully encrypted with TrueCrypt (AES encryption), connected via USB2.0 port. I have bootstrap.dat (21GB copy of blockchain) on the USB drive, too.
Problem
everything is slow via USB2.0 flashdrive. Import of bootstrap.dat  file is barely making progress. It's been 7 days and I'm getting older. The progress bar shows it's 1/3 ready. No other application reads/writes to the USB drive.
Question
I'm considering swapping my flash drive for an external hard drive, but keeping TrueCrypt. Would this help, or would the fact that I have no USB3.0 ports be more important? I'm looking for satisfactory speed results that other people are getting by using bootstrap.dat. As slow as it's going, I'll import the blockchain slower than it's generated.
I would prefer your experience over suggestions like &quot;try this...&quot; becase I don't have free HDD space to &quot;experiment&quot;, I just want to buy some HDD and hook it up to USB, but I'm worried that USB2.0 port itself is a bottleneck and I would just waste money. Thus I'm here for clues.
I'd prefer an HDD instead of an SSD, but I will hear out both options. I'm not interested in thin clients.
(basically I'm looking for cheapest external memory that would work, because flash drives don't work with Bitcoin-QT).
The cheapest external memory that would work fast enough to be acceptable is SATA3 HDD via usb2.0 adapter. (I didn't tested SATA1 or 2 nor old IDE drives, if you have them with over 500GB capacity you can probably use them too. I couldn't find them for my test).
For comparison, here's the time was needed to import 21GB blockchain:


2.0 USB flashdrive: never finished. took 7 days non-stop for progress bar to reach 1/3. and then speed slowed down to the point that there was no noticeable progress.
SATA3 HDD via USB2.0 adapter: about 20 hours non-stop.