Has the performance of physical electronic chess sets increased similarly to the performance of software based implementations over the years? From what I understand, the difficulty of most chess engines is determined by how long they are allowed to 'think' about the moves. From what I understand, the performance of software based chess applications has increased massively over the years, but I'm not sure if hardware limited engines have increased performance in a similar fashion. 

The reason I ask is because my father owns a fairly old electronic chess set, but finds that the advanced levels take too long to compute their moves. I'm wondering if I buy a more modern board, can I assume that a similar level of difficulty can be achieved with less waiting time? For specifics, he already owns a systema Jupiter board, and I'm currently thinking about the Lexibook chessman elite, which is on the cheaper side of things. 

Apologies if this doesn't fit the site's remit, it seems an appropriate place to ask.
There is are basically two features you can look at to decide whether a board computer will be faster: Elo (i.e. playing strength) and processor speed. 

The stronger the maximal playing strength the faster it should be (on comparable levels). Lexibook Chessman Elite should be around 1800, whereas Systema Jupiter Deluxe plays at appr. 1400 Elo. 

I couldn't find the chip speed for Systema Jupiter, but Lexibook has a 2 MHz chip. On this list you can look for something maybe a little faster and a little stronger, though at some point you may have to worry whether the weaker levels are still weak enough. 

I would say that Lexibook, being 400 points stronger, should be comfortably faster than Systema Jupiter.