Otherwise, there's not much I can do to fix the lag on creative:
Spoiler:
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 11.00 135.00 7.00 3560.00 144.00 26.08 1.40 9.79 6.27 89.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 43.00 106.00 4.00 2544.00 376.00 26.55 1.46 13.36 8.00 88.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 7.00 0.00 109.00 0.00 2136.00 0.00 19.60 1.18 10.73 8.62 94.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 141.00 0.00 2760.00 0.00 19.57 1.39 9.86 6.10 86.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 129.00 0.00 2832.00 0.00 21.95 1.00 7.83 5.43 70.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 1479.00 21.00 565.00 512.00 13848.00 24.51 119.14 142.35 1.67 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 387.00 29.00 241.00 320.00 6568.00 25.51 60.54 335.04 3.59 97.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 81.00 59.00 1856.00 1440.00 23.54 3.70 67.86 7.00 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 3.00 0.00 99.00 0.00 1848.00 0.00 18.67 1.17 11.52 8.08 80.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 98.00 0.00 1168.00 0.00 11.92 1.57 16.12 8.16 80.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 69.00 0.00 1448.00 0.00 20.99 0.78 11.45 9.42 65.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 241.00 86.00 240.00 1624.00 2472.00 12.56 10.87 30.58 3.04 99.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 53.00 8.00 1208.00 1448.00 43.54 2.94 62.79 16.07 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 10.00 0.00 121.00 0.00 2016.00 0.00 16.66 2.01 16.61 8.02 97.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 145.00 0.00 3112.00 0.00 21.46 2.81 19.17 6.41 93.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 248.00 0.00 5536.00 0.00 22.32 2.14 8.75 3.95 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 229.00 204.00 155.00 4080.00 3072.00 19.92 4.36 12.17 2.79 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 2501.00 8.00 728.00 72.00 24472.00 33.35 132.43 153.07 1.36 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 36.00 93.00 672.00 2104.00 21.52 18.03 290.47 7.75 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 184.00 0.00 5368.00 0.00 29.17 2.87 17.39 4.95 91.00
In other words: during times of lag, the server is waiting about 1/5th to 1/3rd of a second on average between asking for something from the hard drive, and getting it. Meaning: It waits 2 to 4 ticks loading each chunk from the disk, during that time, no blocks can be placed or destroyed.
sda 0.00 11.00 135.00 7.00 3560.00 144.00 26.08 1.40 9.79 6.27 89.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 43.00 106.00 4.00 2544.00 376.00 26.55 1.46 13.36 8.00 88.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 7.00 0.00 109.00 0.00 2136.00 0.00 19.60 1.18 10.73 8.62 94.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 141.00 0.00 2760.00 0.00 19.57 1.39 9.86 6.10 86.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 129.00 0.00 2832.00 0.00 21.95 1.00 7.83 5.43 70.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 1479.00 21.00 565.00 512.00 13848.00 24.51 119.14 142.35 1.67 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 387.00 29.00 241.00 320.00 6568.00 25.51 60.54 335.04 3.59 97.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 81.00 59.00 1856.00 1440.00 23.54 3.70 67.86 7.00 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 3.00 0.00 99.00 0.00 1848.00 0.00 18.67 1.17 11.52 8.08 80.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 98.00 0.00 1168.00 0.00 11.92 1.57 16.12 8.16 80.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 69.00 0.00 1448.00 0.00 20.99 0.78 11.45 9.42 65.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 241.00 86.00 240.00 1624.00 2472.00 12.56 10.87 30.58 3.04 99.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 53.00 8.00 1208.00 1448.00 43.54 2.94 62.79 16.07 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 10.00 0.00 121.00 0.00 2016.00 0.00 16.66 2.01 16.61 8.02 97.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 145.00 0.00 3112.00 0.00 21.46 2.81 19.17 6.41 93.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 248.00 0.00 5536.00 0.00 22.32 2.14 8.75 3.95 98.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 229.00 204.00 155.00 4080.00 3072.00 19.92 4.36 12.17 2.79 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 2501.00 8.00 728.00 72.00 24472.00 33.35 132.43 153.07 1.36 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 36.00 93.00 672.00 2104.00 21.52 18.03 290.47 7.75 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 0.00 184.00 0.00 5368.00 0.00 29.17 2.87 17.39 4.95 91.00
In other words: during times of lag, the server is waiting about 1/5th to 1/3rd of a second on average between asking for something from the hard drive, and getting it. Meaning: It waits 2 to 4 ticks loading each chunk from the disk, during that time, no blocks can be placed or destroyed.