Speed up solving of MILP model, bound gap is moving slowly

Hi,

I am currently experiencing some challenges in the solving time of a developed MILP model. As soon as I impose an additional set of 3 constraints the bound gap is moving very slowly. I am curious to how I can try to speed up the solving of the problem.

Log:

Gurobi Optimizer version 9.0.3 build v9.0.3rc0 (win64)
Optimize a model with 11106 rows, 46119 columns and 1122626 nonzeros
Model fingerprint: 0x03fed32c
Variable types: 0 continuous, 46119 integer (46078 binary)
Coefficient statistics:
Matrix range [5e-01, 2e+04]
Objective range [1e+00, 5e+03]
Bounds range [1e+00, 1e+00]
RHS range [1e+00, 7e+05]
Presolve removed 5487 rows and 26860 columns
Presolve time: 1.18s
Presolved: 5619 rows, 19259 columns, 322244 nonzeros
Variable types: 0 continuous, 19259 integer (19211 binary)

Root simplex log...

Iteration Objective Primal Inf. Dual Inf. Time
26175 4.1658187e+06 7.748406e+03 0.000000e+00 5s
29780 4.4452147e+06 0.000000e+00 0.000000e+00 5s

Root relaxation: objective 4.445215e+06, 29780 iterations, 4.07 seconds

Nodes | Current Node | Objective Bounds | Work
Expl Unexpl | Obj Depth IntInf | Incumbent BestBd Gap | It/Node Time

0 0 4445214.70 0 5 - 4445214.70 - - 5s
H 0 0 1.028876e+07 4445214.70 56.8% - 6s
H 0 0 7875408.0027 4445214.70 43.6% - 6s
0 0 4864333.95 0 97 7875408.00 4864333.95 38.2% - 7s
H 0 0 5876038.0172 4864333.95 17.2% - 8s
0 0 4938023.96 0 177 5876038.02 4938023.96 16.0% - 8s
0 0 4938023.96 0 5 5876038.02 4938023.96 16.0% - 13s
0 0 4938494.52 0 186 5876038.02 4938494.52 16.0% - 15s
0 0 4944626.55 0 230 5876038.02 4944626.55 15.9% - 15s
0 0 4944627.42 0 230 5876038.02 4944627.42 15.9% - 16s
0 0 4947625.74 0 233 5876038.02 4947625.74 15.8% - 16s
0 0 4947625.80 0 225 5876038.02 4947625.80 15.8% - 16s
0 0 4947632.55 0 224 5876038.02 4947632.55 15.8% - 17s
0 0 4947634.00 0 229 5876038.02 4947634.00 15.8% - 17s
0 0 4947634.00 0 214 5876038.02 4947634.00 15.8% - 19s
0 2 4947634.00 0 211 5876038.02 4947634.00 15.8% - 20s
19 18 4987068.08 5 1 5876038.02 4973076.16 15.4% 181 26s
46 43 4987242.58 10 53 5876038.02 4979756.66 15.3% 147 30s
175 139 4987244.85 32 60 5876038.02 4979756.66 15.3% 65.1 35s
499 341 4982827.13 5 171 5876038.02 4982827.13 15.2% 38.8 40s
1039 695 4987672.80 55 177 5876038.02 4987159.43 15.1% 39.4 50s
1041 696 5819266.09 70 5 5876038.02 4987159.43 15.1% 39.3 55s
1053 704 5334589.96 20 350 5876038.02 4987159.43 15.1% 38.9 60s
1055 706 5293661.20 9 351 5876038.02 4987159.43 15.1% 38.8 65s
1058 711 4987159.43 16 233 5876038.02 4987159.43 15.1% 119 72s
1076 723 5334785.31 19 71 5876038.02 4987159.43 15.1% 121 75s
1107 743 5043243.25 23 154 5876038.02 4987159.43 15.1% 125 80s
1320 822 5370127.00 48 1 5876038.02 4987159.43 15.1% 118 85s
1982 970 5377147.42 103 67 5876038.02 4987159.43 15.1% 91.2 90s
3917 1630 5385987.00 170 1 5876038.02 4987159.43 15.1% 52.3 95s
6537 2612 5396907.00 254 1 5876038.02 4987159.43 15.1% 35.9 100s
8167 2720 5408607.42 345 77 5876038.02 4987159.43 15.1% 33.2 106s
8293 2779 5413027.00 378 1 5876038.02 4987159.43 15.1% 35.0 110s
8678 3076 5426287.00 480 1 5876038.02 4987159.43 15.1% 37.8 115s
9808 3596 5435907.00 554 1 5876038.02 4987159.43 15.1% 37.8 120s
10947 4256 5444747.00 622 1 5876038.02 4987159.43 15.1% 37.5 126s
12034 4922 5454684.20 699 1 5876038.02 4987159.43 15.1% 37.9 130s
14211 5806 5466847.00 792 1 5876038.02 4987159.43 15.1% 36.0 135s
15347 6330 5476467.00 866 1 5876038.02 4987159.43 15.1% 36.8 140s
16567 7175 5485307.00 934 1 5876038.02 4987159.43 15.1% 37.0 145s
19164 8252 5496747.42 1023 77 5876038.02 4987159.43 15.1% 34.3 150s
20253 8661 5508187.00 1110 1 5876038.02 4987159.43 15.1% 34.8 155s
20607 8835 5519367.00 1196 1 5876038.02 4987159.43 15.1% 36.6 160s
20700 8836 5369868.01 340 177 5876038.02 4987159.43 15.1% 37.0 179s
20702 8837 5376108.01 364 5 5876038.02 4987159.43 15.1% 37.0 184s
20705 8839 5378968.01 375 317 5876038.02 4987159.43 15.1% 37.0 185s
20710 8843 5178659.02 1013 381 5876038.02 4987159.43 15.1% 37.0 192s
20712 8844 5157628.00 853 382 5876038.02 4987159.43 15.1% 37.0 196s
20715 8846 5256948.00 1617 391 5876038.02 4987159.43 15.1% 37.0 203s
20717 8847 5425027.85 450 387 5876038.02 4987159.43 15.1% 37.0 206s
20719 8849 5268619.02 1705 388 5876038.02 4987159.43 15.1% 37.0 210s
H20719 8406 5606186.0037 4987159.43 11.0% 37.0 214s
20721 8407 5126399.02 611 396 5606186.00 4987159.43 11.0% 37.0 218s
H20721 7986 5605339.0045 4987159.43 11.0% 37.0 223s
20722 7987 5173245.01 972 355 5605339.00 4987159.43 11.0% 37.0 227s
20723 7987 5605339.00 968 367 5605339.00 4987159.43 11.0% 37.0 230s
20725 7989 5196108.00 1149 369 5605339.00 4987159.43 11.0% 37.0 235s
20729 7991 5166225.01 918 383 5605339.00 4987159.43 11.0% 37.0 248s
20730 7992 5059868.02 101 371 5605339.00 4987159.43 11.0% 37.0 252s
20732 7996 4987159.43 26 240 5605339.00 4987159.43 11.0% 39.1 268s
20734 7998 4987159.43 27 173 5605339.00 4987159.43 11.0% 39.1 277s
20742 8002 5293724.82 28 40 5605339.00 4987159.43 11.0% 39.2 280s
20760 8011 4997721.50 31 216 5605339.00 4987244.07 11.0% 39.5 286s
20785 8019 4998375.85 33 261 5605339.00 4987244.07 11.0% 39.8 290s
20849 8022 5064016.53 38 59 5605339.00 4987244.07 11.0% 40.1 295s

Cutting planes:
Gomory: 16
Cover: 2
Implied bound: 4
MIR: 42
StrongCG: 2
Flow cover: 15
Zero half: 20
RLT: 1
Relax-and-lift: 1

Explored 21550 nodes (883835 simplex iterations) in 300.05 seconds
Thread count was 8 (of 8 available processors)

Solution count 5: 5.60534e+06 5.60619e+06 5.87604e+06 ... 1.02888e+07

Time limit reached
Best objective 5.605339004535e+06, best bound 4.987245000000e+06, gap 11.0269%
Changed value of parameter SolutionLimit to 1
Prev: 2000000000 Min: 1 Max: 2000000000 Default: 2000000000
Gurobi Optimizer version 9.0.3 build v9.0.3rc0 (win64)
Optimize a model with 11106 rows, 46119 columns and 1122626 nonzeros
Model fingerprint: 0x03fed32c
Variable types: 0 continuous, 46119 integer (46078 binary)
Coefficient statistics:
Matrix range [5e-01, 2e+04]
Objective range [1e+00, 5e+03]
Bounds range [1e+00, 1e+00]
RHS range [1e+00, 7e+05]
Presolved: 5619 rows, 19259 columns, 322244 nonzeros

Continuing optimization...


Cutting planes:
Gomory: 16
Cover: 2
Implied bound: 4
MIR: 42
StrongCG: 2
Flow cover: 15
Zero half: 20
RLT: 1
Relax-and-lift: 1

Explored 21550 nodes (883835 simplex iterations) in 0.12 seconds
Thread count was 8 (of 8 available processors)

Solution count 5: 5.60534e+06 5.60619e+06 5.87604e+06 ... 1.02888e+07

Solution limit reached
Best objective 5.605339004535e+06, best bound 4.987245000000e+06, gap 11.0269%
Changed value of parameter TimeLimit to 299.87730407714844
Prev: 300.0 Min: 0.0 Max: inf Default: inf
Changed value of parameter SolutionLimit to 1999999999
Prev: 1 Min: 1 Max: 2000000000 Default: 2000000000
Gurobi Optimizer version 9.0.3 build v9.0.3rc0 (win64)
Optimize a model with 11106 rows, 46119 columns and 1122626 nonzeros
Model fingerprint: 0x03fed32c
Variable types: 0 continuous, 46119 integer (46078 binary)
Coefficient statistics:
Matrix range [5e-01, 2e+04]
Objective range [1e+00, 5e+03]
Bounds range [1e+00, 1e+00]
RHS range [1e+00, 7e+05]
Presolved: 5619 rows, 19259 columns, 322244 nonzeros

Continuing optimization...

21550 8061 4987245.00 33 1 5605339.00 4987245.00 11.0% 39.4 300s
21748 8030 4993828.08 84 1 5605339.00 4987245.02 11.0% 39.3 320s
23997 8349 5032827.88 384 1 5605339.00 4987245.02 11.0% 36.5 325s
26446 8149 5081885.00 761 1 5605339.00 4987245.02 11.0% 34.4 330s
29664 7733 5129547.88 1128 1 5605339.00 4987245.02 11.0% 31.5 335s
32159 7546 5172448.08 1458 1 5605339.00 4987245.02 11.0% 29.5 340s
33966 7396 5210667.88 1752 1 5605339.00 4987245.02 11.0% 28.3 370s