You can conserve RAM by loading samples ONLY into the intended range of an
instrument.
Some popular instrument ranges can be found here.
NOTE: These ranges are non-transposed and where Middle C = C3.

VIOLIN:        G below C3 to C6
VIOLA:         C2 to C5
CELLO:         C1 to C5
BASS:          E below C1 to C2
FLUTE:         C3 to C6
OBOE:          Bb below C3 to G above C5
CLARINET A:    C# above C2 to F# above C5
CLARINET Bb:   F below C3 to G above C5 
BASSOON:       Bb below C1 to Bb below C4
ENG. HORN:     E2 to Bb4
TRUMPET:       G below C3 to Bb below C5
MUTED TRUMPET: G below C3 to Bb below C5
TROMBONE:      E above C1 to Bb below C4
ALTO SAX:      Db above C2 to Ab above C3
TENOR SAX:     Ab below C2 to Eb above C3
BARITONE SAX:  Db above C1 to Eb above C3
HARP:          C0 to Bb below C6
GUITAR:        E above C1 to A above C4
VIBES:         F below C3 to F above C5