I've seen recently a trend where code is optimized for run time and memory consumption is a distant second consideration.  I think this is a side-effect of the growth of big data,  where you really do have to worry about your run time.  Unfortunately this seems to have creeped into a lot of other types of coding where it doesn't make a much sense.

For example, it's not uncommon to see data stored in hash tables which admittedly are fast to retrieve if you use the right hash table key.    But since most programmers don't think through the overhead of the key portion of the table, you'll often see many hash tables each containing the exact same set of keys, each holding one data item (say a distance in a routing table).   A more memory efficient method is to store a structure in the hash table containing all the values.  That way they only pay the key "tax" once. 

I could vent about all sort of other sins like this.