( ( Since ( ( ( the amount ) ( of ( time ( ( we ( -LRB- ( usually -RRB- ) ) ) ( spend ( processing ( ( the data ) ( ( is negligible ) ( compared ( to ( ( the amount ) ( of ( time DOS ) ) ) ) ) ) ) ) ) ) ) ) ) ( takes ( to ( ( ( return or ) write ) ( the data ) ) ) ) ) ) ( , ( ( ( reading ( two characters ) ) ( at ( a time ) ) ) ( ( ( will essentially ) ( double ( ( the speed ) ( of ( the program ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Since) (S (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN time)) (SBAR (WHNP (NP (PRP we)) (PRN (-LRB- -LRB-) (ADVP (RB usually)) (-RRB- -RRB-))) (S (VP (VBP spend) (S (VP (VBG processing) (SBAR (S (NP (DT the) (NNS data)) (VP (VBZ is) (ADJP (JJ negligible)) (PP (VBN compared) (PP (TO to) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN time) (NN DOS))))))))))))))))) (VP (VBZ takes) (S (VP (TO to) (VP (VB return) (CC or) (VB write) (NP (DT the) (NNS data)))))))) (, ,) (S (VP (VBG reading) (NP (CD two) (NNS characters)) (PP (IN at) (NP (DT a) (NN time))))) (VP (MD will) (ADVP (RB essentially)) (VP (VB double) (NP (NP (DT the) (NN speed)) (PP (IN of) (NP (DT the) (NN program)))))) (. .)))
Since the amount of time we (usually) spend processing the data is negligible compared to the amount of time DOS takes to  return or write the data, reading two characters at a time will essentially double the speed of the program.
(ROOT (S (S (NP (DT This) (NN process)) (ADVP (RB usually)) (VP (VBZ takes) (NP (NP (DT the) (JJS longest) (NN amount)) (PP (IN of) (NP (NN time)))))) (: :) (S (NP (DT an) (NN ocean) (NN basin)) (VP (VBZ forms) (PP (IN between) (NP (CD two) (NNS continents))))) (. .)))
This process usually takes the longest amount of time: an ocean basin forms between two continents.