In jBASE 5.8, an enhancement to the BASIC (aka jBC) compiler has made comparisons against '' (empty string) dramatically faster.

Historically it was quicker to compare the LEN() of a variable against 0 to test if a variable was '' (NULL).

For example if you're on 5.7 (or earlier) try the sample code.

workVar = STR('the quick brown fox jumps over the lazy dog', 10000)
startTime = SYSTEM(12)
FOR I = 1 TO 10000
    IF workVar NE '' THEN
    END
NEXT I
CRT 'First FOR loop took: ':SYSTEM(12)-startTime

startTime = SYSTEM(12)
FOR I = 1 TO 10000
    IF LEN(workVar) THEN
    END
NEXT I
CRT 'Second FOR loop took: ':SYSTEM(12)-startTime
​

On 5.8 the statement:

IF workVAR NE '' THEN

now gets compiled to a special function (this is also true for EQ '') that performs the same as

IF LEN(workVar) NE 0 THEN

so the sample program (above) will produce similar results (depending on system usage).